Using GNOME (I run on Ubuntu), here are the mime and lang-spec for LoLCode

<code bash>
cat /usr/share/gtksourceview-2.0/language-specs/lolcode.lang
</code>
<code xml>
<?xml version="1.0" encoding="UTF-8"?>
<!--

 Author: Sébastien Lavoie <lavoiseb@iro.umontreal.ca>

 This library is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

-->
<language id="lolcode" _name="LolCode" version="2.0" _section="Scripts">
  <metadata>
    <property name="mimetypes">text/lolcode</property>
    <property name="globs">*.lol</property>
    <property name="line-comment-start">BTW</property>
    <property name="block-comment-start">OBTW</property>
    <property name="block-comment-end">TLDR</property>
  </metadata>

  <styles>
    <style id="comment" _name="Comment" map-to="def:comment"/>
    <style id="error" _name="Error" map-to="def:error"/>
    <style id="escape" _name="Escaped Character" map-to="def:special-char"/>
    <style id="string" _name="String" map-to="def:string"/>
    <style id="keyword" _name="Keyword" map-to="def:keyword"/>
    <style id="operator" _name="Operator" map-to="def:operator"/>
    <style id="type" _name="Data Type" map-to="def:type"/>
    <style id="null-value" _name="Null Value" map-to="def:special-constant"/>
    <style id="boolean" _name="Boolean value" map-to="def:boolean"/>
    <style id="floating-point" _name="Floating point number" map-to="def:floating-point"/>
    <style id="decimal" _name="Decimal number" map-to="def:decimal"/>
  </styles>

  <definitions>

    <context id="cpp-line-comment" style-ref="comment" end-at-line-end="true" extend-parent="false">
      <start>BTW</start>
      <include>
        <context ref="def:in-line-comment"/>
      </include>
    </context>

    <context id="c-block-comment" style-ref="comment">
      <start>OBTW</start>
      <end>TLDR</end>
      <include>
        <context ref="def:in-line-comment"/>
      </include>
    </context>

    <context id="close-comment-outside-comment" style-ref="error">
      <match>TLDR(?!TLDR)</match>
    </context>

    <context id="escape" style-ref="escape">
      <match>\:(\:|\)|\>|o)</match>
    </context>

    <context id="string-var">
      <include>
        <context id="curly-var" style-ref="variable" >
          <start>:{</start>
          <end>}</end>
          <include>
            <context ref="string-var"/>
          </include>
        </context>
      </include>
    </context>

    <context id="double-quoted-string" style-ref="string">
      <start>"</start>
      <end>"</end>
      <include>
        <context ref="escape"/>
        <context ref="string-var"/>
        <context ref="def:line-continue"/>
      </include>
    </context>

    <context id="keywords" style-ref="keyword">
      <keyword>AN</keyword>
      <keyword>MKAY</keyword>
      <keyword>SUM OF</keyword>
      <keyword>DIFF OF</keyword>
      <keyword>PRODUKT OF</keyword>
      <keyword>QUOSHUNT OF</keyword>
      <keyword>MOD OF</keyword>
      <keyword>BIGGR OF</keyword>
      <keyword>SMALLR OF</keyword>
      <keyword>BOTH OF</keyword>
      <keyword>EITHER OF</keyword>
      <keyword>WON OF</keyword>
      <keyword>ALL OF</keyword>
      <keyword>ANY OF</keyword>
      <keyword>NOT</keyword>
      <keyword>BOTH SAEM</keyword>
      <keyword>DIFFRINT</keyword>
      <keyword>SMOOSH</keyword>
      <keyword>VISIBLE</keyword>
      <keyword>INVISIBLE</keyword>
      <keyword>GIMMEH</keyword>
      <keyword>R</keyword>
      <keyword>A</keyword>
      <keyword>EXCL</keyword>
      <keyword>NUMBR</keyword>
      <keyword>NUMBAR</keyword>
      <keyword>VAR</keyword>
      <keyword>YARN</keyword>
      <keyword>BR</keyword>
      <keyword>MAEK</keyword>
      <keyword>IS NOW A</keyword>
      <keyword>O RLY?</keyword>
      <keyword>YA RLY</keyword>
      <keyword>NO WAI</keyword>
      <keyword>OIC</keyword>
      <keyword>MEBBE</keyword>
      <keyword>WTF?</keyword>
      <keyword>OMG</keyword>
      <keyword>OMGWTF</keyword>
      <keyword>GTFO</keyword>
      <keyword>IM IN YR</keyword>
      <keyword>IM OUTTA YR</keyword>
      <keyword>YR</keyword>
      <keyword>TIL</keyword>
      <keyword>WILE</keyword>
      <keyword>UPPIN</keyword>
      <keyword>NERFIN</keyword>
      <keyword>HOW DUZ I</keyword>
      <keyword>IF U SAY SO</keyword>
      <keyword>FOUND YR</keyword>
    </context>

    <context id="operators" style-ref="operator" extend-parent="false">
      <match>[\!\,]</match>
    </context>

    <context id="type" style-ref="type">
      <keyword>BUCKET</keyword>
      <keyword>TROOF</keyword>
      <keyword>NUMBR</keyword>
      <keyword>NUMBAR</keyword>
      <keyword>YARN</keyword>
      <keyword>NOOB</keyword>
    </context>

    <context id="null-value" style-ref="null-value">
      <keyword>NOOB</keyword>
    </context>

    <context id="boolean" style-ref="boolean">
      <keyword>FAIL</keyword>
      <keyword>WIN</keyword>
    </context>

    <context id="float" style-ref="floating-point">
      <match extended="true">
        (?&lt;![\w\.])
        ([0-9]+[Ee][+-]?[0-9]+ |
         ([0-9]*\.[0-9]+ | [0-9]+\.[0-9]*)([Ee][+-]?[0-9]+)?)
        (?![\w\.])
      </match>
    </context>

    <context id="decimal-number" style-ref="decimal">
      <match extended="true">
        (?&lt;![\w\.])
        [+-]?([1-9][0-9]*|0)
        (?![\w\.])
      </match>
    </context>

    <context id="lol-block">
      <start>HAI</start>
      <end>KTHXBYE</end>
      <include>
        <context sub-pattern="0" where="start" style-ref="keyword"/>
        <context sub-pattern="0" where="end" style-ref="keyword"/>
        <context ref="cpp-line-comment"/>
        <context ref="c-block-comment"/>
        <context ref="double-quoted-string"/>
        <context ref="keywords"/>
        <context ref="operators"/>
        <context ref="type"/>
        <context ref="null-value"/>
        <context ref="boolean"/>
        <context ref="float"/>
        <context ref="decimal-number"/>
      </include>
    </context>

    <replace id="html:embedded-lang-hook" ref="lol-block"/>

    <context id="lolcode">
      <include>
        <context ref="lol-block"/>
        <context ref="html:html"/>
      </include>
    </context>

  </definitions>
</language>
</code>

And the mime
<code bash>
cat /usr/share/gtksourceview-2.0/language-specs/lolcode.lang
</code>
<code xml>
<?xml version="1.0" encoding="UTF-8"?>
<mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info">
   <mime-type type="text/lolcode">
      <sub-class-of type="text/plain"/>
      <comment>LolCode Source Code</comment>
      <glob pattern="*.lol"/>
   </mime-type>
</mime-info>
</code>