Can he cum while she knees him?

Sierra just finished getting herself off with a hitachi with one foot on her slaves face and the other on his balls. Now she's going to be generous and let him cum as well…… if he can :)............................................................. She grabs him by the balls and pulls him onto his feet, and tells him to stroke his dick. She wants to know if he can cum while she's kneeing him in the balls. She's only going to give him a little time to work his cum out while being kneed in the nuts, but if he can, he get's to cum on her pantyhose clad leg, (and lick it all off of course)......................................................................... Sierra has been beating on his nuts all weekend, and his balls are sore and extra sensitive. ............................................................................................ She teases him with her ass, "Don't you wish you could be fucking me?" and he would be if his dick was big enough to satisfy her…............................................ Sierra threatens him that he better cum now because if he doesn't she'll leave him with blue balls, and if she finds out he jerked off after she leaves, she'll castrate him. She will cut his balls right off and through them down the garbage disposal :) .................................................... Sierra get's extra cruel and tells him he can touch her perfect tit's, but when he does she squeezes his balls almost until they pop and says "you can hold on as long as you want, but I'm just going to keep squeezing :)" He desperately wants to keep her perfect round titty in his hand but he's terrified she'll actually pop one of his nuts……............................................... She finally tells him that she wants him to cum all up and down her leg, and if he fucks it up, she's going to squeeze his balls off :)............................................. Once he finally cums she rubs his face in it and walk away….