Whoever thinks masturbation and penis jokes are immature and crass: beware.

Brian Posehn filled his set of comedy last night with self-deprecation and asides about his own dark twisted fantasies. RANDY SCHAFER/Staff

That they may be, but watching Brian Posehn tell ‘em, I laughed, really — to the point I could feel my abs clinch.

I knew it was going to be a good time when he said to start, “Just so you know, you can take off your thinking caps, ’cause it’s about to get super f—— stupid in here.”

Posehn’s jokes about the horrors of the Clermont Lounge in Atlanta, or tramp stamps right above what he refers to as the “the B-hole,” were described so vividly I could relive tossing crumbled up ones at the strippers who’ve been in the trade longer than I’ve been alive.

He referred to his experience as a “nightmare he can never forget,” full of scenes “that are still burned into my retinas.”

I was holding my sides when he joked about drunken “brojobs” and yelling “Slayer” to counteract homosexual encounters, hooking up with male friends, which became an underlining theme throughout the act.

The raunchy, sometimes shocking humor of Posehn was often met with uproars of laughter or the occasional groan when he mentioned masturbating while his baby was crying or his graphic joke about having sex with “neck vaginas.”

When he talked about being caught masturbating in his “nerd cave” and his experiences with raising his son, I was struggling to breathe.

Posehn played on the notions of his nerdy lifestyle and his shortcomings, making references to his rather large, ogre-like appearance or his “rapey-face” and joking about how he can’t sneak up on people or dig ditches at night.

A couple of his jokes fell short, but that’s expected when trying out new material — something he previously cautioned to the audience.

But all the less amusing jokes were long-forgotten after hearing his drawn-out masturbation fantasy that included having sex with the girl he saw at Starbucks and being on a train engulfed in flames while forcing Megan Fox to watch in the background.

Without beating a dead horse — or overly beating the meat, so to speak — Posehn snuck in a couple more masturbation  jokes about his adolescent “Star Wars” penis reenactments and how his mother showed him the way to his spunk-filled path.

…Which by the end of the night had left me numb and wanting more.