(2) A generic filler word that can be used in a multitude of situations, ranging from vulgar to commonplace.
(3) The skin located in the crook of the knee.
Person #2: Oh, man! That's so cleesh!
Person #1: Her skirt was so short that her cleesh was hanging out!
Person #2: Oh my god! She's such a slut!
Person #1: I have a huge test tomorrow that I didn't study for.
Person #2: Cleesh, man. Cleesh.