I'm glad you raise this. Come guys and any girls full honesty has this ever ever worked. Never done it so honestly can't believe it has. What are these people on.Haha, wtf? Really? And it was only later he realised this was wrong? Surely the fun is in that it is obviously wrong? Otherwise WTF is going on in their heads? Honestly, wtaf?
Giving it some thought, possible options:
"She'll fall in love with me once she sees my slightly-bigger-than-average pecker"
"She says she likes vulnerable guys... fuck it. *ziiiip*"
"Nothing says 'I want you' like a dick-pic"
"Shit! I forgot to press 'switch to face-cam'"