On Tue, 20 Nov 2007 23:17:17 -0500, somebody wrote:

I have a 1/2 a bathroom in my garage. Occasionally I'll find a slug on
the toilet seat. Many times over the years I've found 2 or more of them
on the toilet! This doesn't occur very frequently, maybe 4 - 6 times a
year, but sometimes more. Usually I'll go for months without seeing one.
Since I never see any slugs on the floor, or anywhere except for the
toilet, I'm guessing that they're coming up through the sewer pipes.
Does that sound reasonable? Also, what could I do to prevent them?
Slug traps? Kidding! Actually I tried pouring some bleach in the
toilet.

Clean up vegetation and organic materials around foundation. Sprinkle
diatomaceous earth around foundation to discourage slugs. This can be
found in most gardening centers. Caulk or foam cracks.