pillow sweat

Pillow sweat is when you wake up and your pillow is soaking wet, it could either be from crying, slobbering or sweating. Either way, if you see it on someone's pillow don't sleep there.

Nicole: I went over Bob's house and slept over the night, and when he woke up I saw pillow sweat on his pillow.

Lana: Ugh! He was probably crying.