I remember it was in one of the few videos that I saw... Two guys were doing one girl. It was a DP. When the first guy was about to cum, they changed the position, and the second guy was just sitting and waiting for her to recieve cum from the 1-st guy.
It took some time, and his dick, which was suspiciously soft from the very begining, went completely limp. So he started do jerk with apathy on his face. When girl finished with 1-st guy, she went back to the second. Having noticed that he was jerking, she decided to wait until he came and put her face nearer to recieve cum. But dick was still soft. What an awkward situation! The guy felt it too, and he understood that it was his fault - what is a pornstar if he can't keep his dick hard?!
But he decided to take it out on girl, and stopped to jerk, showing her with a gesture to continue the job. In a combination with the grievance and anger on his face it looked very stupid and funny, just like:
"c'mon, do not you see this dick is so soft? do not you see I can't make it hard myself? shit! so do your fucking job, little bitch, fix it somehow! be a woman!"
when people feel that they are weak, they often try to substitute their weakness with attacks on someone else, pretending that it is their fault.
I guess it was very annoying :1orglaugh