Masturbation...with disastrous results.
Theres no such thing as the verb, "disasturbate" because you never plan it. Disasturbation is the result of a failed attempt. Disasturbation just happens, and boy does it suck when it does.
(n) term used to describe when pleasuring oneself ends tragically with an unfortunately timed interruption
"I was jacking off and my cat jumped on my lap right before i came. It was a terrible disasturbation session."
"Then a couple days later, my mom decided to barge into my room to wake me up as i was cranking it under my sheets. I disasturbated twice this week."
To masturbate during a disaster, or when normal masturbation turns disastrous.
Masturbation turns into disasturbation if you're arrested for doing it in public.
The act of masturbation with such ferocity that you actually rip your penis off.
"Dear god - I have ripped my own penis off. I must tell no one about this distasturbation mishap."