Ask him

He has been patient with you and you really only know how to use your mouth to engorge a manhood, perhaps there is a better way and if so the best way to find out would be to ask. You pause for a few seconds whilst considering how to ask the man the best way to get him hard but decide you should make a observation and then enquire over solutions to the problem at hand. So calmly but sternly you state.

"You appear to have gone a little flaccid whilst I."

"Sorry. I'll sort that."

The man blurts back and quickly withdraws his penis from the hole. It was not the answer you were expecting but you can hear movement on the other side of the thin wall. You realise that whatever he is doing is what a man must do to erect himself, and although you were hoping that he would just tell you what to do observing it first hand would also work. But watching him through a hole, even if it is a hole used for such lewd acts, seems a little rude.

On the other hand you've half caught the next on screen girl 'confessing' how she enjoys to masturbate, and is then promptly demonstrating her enthusiasm with the mans reply being that masturbation on both holes can be good preparation for sexual activity. You watch as she sinks a finger into her own behind much to the delight and encouragement of her on screen partner. Perhaps you should 'prepare' yourself in a similar way?