Best definition
To be able to wank as good with your left hand as with your right.

I tested myself to see if I was wankidexterous last night, buy now my johnson is just sore.
wankidexterous: define #2
Being able to masturbate with both hands.
“Hey how are you going to masturbate now that you’ve broken your arm?”

“No worries, I’m wankidexterous”