Its etymology is widely disputed but latest research has proven that it was first used by a certain boy in the german town "Rheine" who randomly rearranged the letters on his keyboard during a horrendously boring english lesson and here by accidentally discovered it. It is a fusion of the words "penis" and "swag."
Combined, these words have no meaning but what one might try to convey through the sentence and it's verbal delivery. It can be used as a verb, a noun, an adjective and an adverb.
A Peniser is a chronic and dedicatedMasturbator. Most Penisers penis their penis for hours at a time and are very proud of being Masturbators.
Steve: I know Tony is a Peniser.
Rick: How do you know?
Steve: I saw him penising himself all day on Chaturbate yesterday.
Rick: Wow, I would have never guessed, he seems like such a nice guy