How can I stop Syntext Highighting in MyBB with a mod

[ZiNgA BuRgA]

If it's a MyCode, it shouldn't have this.
If it's a plugin, it may be affected.  If you have to implement it as a plugin, you may wish to try to reverse the effects of the highlight, or completely disable it.  An alternative method may be to try to insert your regular expression into the MyCode cache so that it's somewhat treated like a custom MyCode.