Minuki/見抜き/見ぬき: 見る(to see/look) + 抜く(to ejaculate/masturbate). This word was originally used in MMOs to refer to the practice of masturbating to a fantasy while looking at a female avatar (not necessarily particularly sexual), but it now seems to be used simply to masturbate in front of the other person.
BTW, the fact that characters often ask for permission in artwork for these situations, such as post #3759530 and post #2682684, may have been influenced by this exchange, which also became the official LINE stamp of the game.