A potentially painful condition in which a male, often wearing boxers or no underwear, is walking or jogging and the testicles and/or flaccid penis repeatedly slaps against the inner thighs.
Jogger Chad: "Dude... ok, I gotta take a break here..."
Jogger Michael: "Aw, man come on... we got three miles to go."
Jogger Chad: "Dude... fucking got pendulum penis going on right now, k? Gimme a freaking break."
Jogger Michael: "For Christ's sake, you said that two minutes ago."
Jogger Chad: "Fuck off! I thought I had the testies of Papa Smurf last time I tried to tough it out... couldn't beat off for two days."
After gravity has taken it's toll upon the male genitalia a man can now use his scrotum and testicles as a wreaking ball. Assuming he has two, one needs to bounce back into the other testicle sending it hurdling towards the desired object. Thus the pendulum effect.
Bro: How did you get that hole in your bathroom wall?
You: I realized I forgot a towel when I got out of the shower so I was going to helicopter myself dry with my giant schlong but I accidentally pendulum smacked the wall.
A position taken by someone reacting to a perceived dominant narrative they disagree with that is a complete overreaction and overreach in the opposite direction.
"Pitbulls are actually the sweetest, most harmless dogs ever to exist."
"Bit of a pendulum take, don't you think?"