Well..lol icechat.. anyway

on *:TEXT:!aai*:*:/me $nick aait door de wilde haartjes van $2 tot $2 begint te spinnen van plezier!
on *:TEXT:!aaibaar*:*:

It might have something to do with haveing commands that match each other

Or

on *:TEXT:!aai*:*:/me $nick aait door de wilde haartjes van $2 tot $2 begint te spinnen van plezier!

this has a $2...which might not be filled.

There are random chunks of script that are ...weird

Code:
on *:TEXT:!bloosje	$2 zou beter nick verandere naar bloosje want bij elk lief kusje of knuff'ke krijgt em/ze rooie kaakskes {;)} :p


My guess is that your issue with !aai is because $2 isn't filled...but then again You aren't using mirc soo--weird place to ask about that error message.