what if someone makes fun of you for masturbating?

Cock slap them

Just laugh back, since they do it too.

"I've been meaning to ask if you wanted to help. You seem pretty interested." If it's a good friend or your bro, you don't get upset, you say, "yeah, and I'm gettin' pretty good at it."

Then that may make them a hypocrite. Listen- its completely natural and normal to do. If someone is making fun of you for doing a normal thing, shrug your shoulders. It's really not a big deal.

just say go fuc-k yourself

How would they even know you do? If they know for certain and you aren't the one telling him or her, you need a better door lock. Or something. To guarantee privacy.

Ignore them since they do it too.

its time to find a better place to do it

Laugh with them.

If you get angry or ashamed... they will just double down, but if they think it doesn't bother you they will eventually drop it.

I'd probably shrug in a way that says I don't give a sh*t.

Or I'd say something smart like, "So you think about me masturbating a lot?" or "And? OH! I get it. I'm really flattered. Really, I am. But it's gonna have to be a thanks but no thanks."