its a relatively non affensive insult taking the words 'penis' and wanker' and combining them to make something not quite as good as either.
man 'oh, this idiot stole my car and killed my dog'
man2 'what a penistic winker'
Capitalism, where everyone gets a penis!
Used in Psychology student circles when debating outdated Freudian theories and concepts, like 'penis envy', in the context of contemporary gender issues.
Person A: I have a penis envy, and I can't compete with mom for dad's attention (AKA Electra complex), so I'll get a penis myself.
Person B: It's capitalism! Everyone can get a penis!
Person A: Penistalism!!!
It's not that word, it is referring to people who play with a pen in class.
I myself play with pens in class.
OMG THE PENIST IS PLAYING WITH HIS PEN IN CLASS!!!!
OMG THE PENIST HAS A BLACK PEN!!!!