Computer and Water damage, not sure?

I had friends over the other night and I think one of them may have spilled on my MBP, it was sleeping and it was closed and the top had a bit of damp and the sides did as well I looked and didn't see too much more a little around my kensington lock but now I am worried about my computer how can I tell and is there any check ups or anything I can do except get different friends. Thanks