Expression of agreement, sympathy, acknowledgment and a sign that you approve or comprehend a given action, thought, or situation. Essentially, this is the shortened expression of: "I feel that."
Chester: Hey, what did you do today John?
John: I banged
two girls, and then went to the gym and benched 300lbs like it wasn't nothing.
Chester: Damn, John, I feels!
Josh: Hey man, you're sister is HOT!
Chester: Man, WTF
, I don't feels that, feels OFF her, bro.
Josh: But, c'mon man, you don't at least feels me on that subject?