as far as I know there is no other way than to color the text the same as you have your normal text and background.
this will look fine to you, but if anyone else has different colors it wont match theirs.
using ctrl+o ($chr(15)) or ctrl+k ($chr(3)) will not stop the color, as its not colored in the same way to the program.

so here is some
Code:
on *:ACTION:Give*:#:{
  if ($me == StupBot) {
  if ($4- == cookie ) { describe $chan $+(*,Takes $4-,*) 1,0SNARF! }
  else if ($4- == pepsi) { describe $chan $+(*,Takes $4-,*) 1,0Thanks! }
  else if ($4- == coke) { describe $chan $+(*,Takes $4-,*) 01,1I like Pepsi better... Unless it's Vanilla Coke! }
  else /msg $chan No thanks!
  }
}