If the review is meant to be humorous AND tickles my funny bone, I hit the FUNNY button.
If the review is so absurd it makes me laugh, I hit the FUNNY button UNLESS it's really sad, in which case I hit no button 'cause SAD isn't an option.
I get lots of FUNNY votes for my serious reviews. Big deal!
Note: Those who wish to give me more FUNNYs are cordially invited to rate all my reviews:
http://tinyurl.com/yo6nod