I spilled a gallon of latex paint down my bathroom sink. What should I do?

Fill your sink with warm water and drain it, repeat about 5 times. The first few will go slow until the latex gets out of the trap. Continue 5 more drains after the sink drains quickly. Do this right way, do not let the paint start to dry or thicken. If you have sinks on a higher level, fill that too and drain it at least once or twice.

You are lucky because latex paint dissolves in water. Not too quickly - but it does. Do what ballengerb1 said and you should be just fine.

Thanks for answering so fast.

I am attempting this but if its draining; it is extremely slow. There was already some water in the sink when I spilled the paint. I just went in and added enough hot water to the point of not going over the overflow holes. It has been about an hour and the sink was only about halfway drained. Should I try liquid plumber or just wait to drain? I could try pouring hot water from another source right into drain opening. Any ideas?

An hour? That indicates that you created yourself a cloggage. I would take your P-Trap ( that's the J-shaped pipe under your sink ) apart first to see if it is clogged up there. There is still a chance that your pop-up assembly is holding the clog.

Ok. I am flowing now. Using hot water helped. I am going to continue to flush it 5 times like you said. But I think its going to be OK. Thanks so much for your help.

Good job and use of patience. Glad you did not add Liquid plumber to that sink. Try to avoid strong chemicals, they are for folks who don't know the AMHD address.