When a girl walks down the street in such a short skirt and with an anal plug, it's clear that she's looking for an adventure for her ass. Licking ice cream is just an added touch to this image of a bitch. So her verbal signs were quickly understood and she even squirted while being fucked in the ass.
I don't know why she had to tie her boyfriend up like that, what would he do if his hands were free? Would he have messed up the redhead's hair or prevented his boyfriend from getting his dick out of his pants? I'm sure he would have sat quietly with his hands free as well.