Hello! this very common word is called, in english, masturbating. Don't be disturbed by this.

Grammar note: you will see...

... that the verb can be reflexive. I suppose it would be surprising if that verb -- of all verbs -- could not.

That's hilarious (to me).

Haven't looked at the clip yet. Fear, you know! (I'm laughing as I type)

Masturbacion
Oneself: masturbarse
Someone else: masturbarle/la/les/las
Onanismo too