The sound you make when you;
1. are
cheating on, or don't know the answers on the test, but to avoid the
teacher's attention, you fake being in deep thought.
2. Someone close to you (in person) asks you a very confusing question (usually for the jokes) or a very hard question, you make this sound while thinking about it, before answering.
3. are in
deep trouble, usually with a significant other or parent, and when they ask you something along the lines of "What did you do wrong?" trying to make you confess so you feel guilty. If you decide to piss them off further, you make this sound despite knowing full
well what you did wrong.
(1.) Jim: cheating on the test, when he notices the
teacher is coming
Also Jim: Starts rubbing his chin "thoughtfully" "Hmm..."
Teacher: may have noticed what he was doing, may have been oblivious, but the anxiety of whether the teacher knew or not would be eating Jim up from the inside.
(2.) Friend: "What came first, the chicken or the
egg?"
Me: "Hmm..."
Also me: "Well, the
egg, because evolution occurs through childbirth and..."
(3.) Pissed off GF: "What did you do wrong tonight?"
BF: decides to be an
asshole "Hmm... I don't really know! What did I do to
ya?"
GF: becomes a literal tomato "YOU ASSHO-" throws something at him