I was wondering to know why my bf's legs always shake when i'm doing him a blowjob. First of all i wouldn't say it's from excitment/nervousness nor orgasm (he wasn't close to it by that time) and that is confirmed each time i just start palying with it out of fun not specificlly to make him go crazy or plan something to happen, sometimes i even know the ways to put him to sleep with it (so he can be very relaxed), but as he's holding his legs spread and folded in knees after some time they would start to shake - firt just a bit, just vibrating, and then getting more and more to the point they would shake violently and uncontrolable(and i will repeat he wasn't even close to orgasm and he wasn't nervous, coz it happened each time i do it and we are together for 2 years!!!). He or I would have to hold them to stop from shaking, otherwise they would be just shaking all over the place (i can't do it always since i'm doing the blowjob so not in a possition to constantly hold the weight of his legs on my arms).
Does anyone can please tell me what the shakes means? Any wild guess would help clear it....
Thanks!