According to the Chicago Sun-Times:

Contrary to reports elsewhere, the Bulls have no interest in taking back Washington center Etan Thomas in a trade for Larry Hughes. The Bulls like Thomas - just not the extra $2 million kicker to the $7 million annual salary he is due by contract if traded. Guard Mike James ($6 million per season) also was rumored to be in the Wizards' package for Hughes, who is due $13.5 million next season.

What is this "kicker" that is being referred to?  This is the first time I have read about this.  Can someone please explain to me what this means?

This is probably why we can't unload Etan despite his expiring contract.  Ernie is starting to look a lot less smart than I previously gave him credit for.