Send them a bigger one, one with future

or they have a humiliation or exposure fetish

But I just remembered that some guy messaged me last week, and after about 5 minutes of talking he asked if I wanted to see his dick. I said no, but he went ahead and sent three anyway, tyen acted like I was being stupid for being mad about it, and insisting that I secretly wanted it. I had to lie about having a boyfriend to get him to back off
Those guys are absolute scum

You should have send him horse genital back
Every time some dude sends me nasty things
I wanna send them something say worse back

I'm a guy and I don't have the confidence to send a pic of my face, let alone my dick

There's plenty of dick amputation or castration photos you can send back.

If a guy sends you a random dick pic send him a bigger one back

I don't get unsolicited dick pics, but here's some stuff to send back.
1) Make fun of it
2) A picture of a penis amputation
3) Tell him you're gay
4) Send that one gif of a hot dog getting sliced into lots of pieces

A good idea combining horse genitals and amputation/castration: pictures of a horse cock, then gelding. Verb, not noun.

Fuckboys get horny, think of any girl they've ever met other than family, and send a pic. I don't think they realize it's not sexy.

Dicks look gross in general tbh. Especially when photos are taken from unflattering angles.

Genitals can be attractive (to me at least)
But not like I just gonna lose myself after seeing a random pretty-good looking dick