Abu is correct; 79% of the time, beer works every time.

Funny story (well, maybe someone will think it's funny):

A couple of years ago after Halloween, my wife got really tired of looking at and dealing with slugs, so she dumped half a beer in one of our jack-o-lanterns. A few days later, we had what might have been the most disgusting cocktail of rotting pumpkin, stale beer, and drunken-to-death slugs you would ever want to see. Naturally, the job of disposing of the foul concoction fell to your's truly. I made it about 20 feet before the bottom of the pumpkin gave way, dropping the full volume of beer/slug swill all over my legs and feet. Few feelings I have known have been anywhere close to as disgusting, and the smell was worse.

After a series of dry heaves and a profanity-rich cleanup session, I calmly asked my wife to use something other than jack-o-lanterns for future slug traps. She laughed at me, but later complied.

I will have to try the alternatives suggested; seems they might produce less ungodly by-product.