Tandem bike 

(N.) A group of women who are on same menstrual cycle.

"After working here for three months, it was only a matter of time before I was added to Mary and Ashley's tandem bike."

Tandem bike by Leon Firestone December 29, 2012

Tandem Turd

A turd that reaches both ends of the toilet.

I ate so much McDonald’s that i clogged the toilet with a tandem turd!

Tandem Turd by Pizzasuacc July 26, 2019

Tandem Shitting 

The act of two people taking nasty shits in side by side bathroom stalls at the same time.

Baxter "Did you see those two guys go into the bathroom and drop bombs at the same time"?

Jay "Ya Tandem Shitting is frowned upon".

Tandem Shitting by MadShitter40 January 12, 2012

Tandem Mudslide 

This can only be done in prison. When you have to take a shit real bad and there is only one toilet to shit in and it is in use. You sit on the other shitters lap, while he spreads his legs slightly to allow your shit to drop between his legs into the bowl.

Also known as David Hasselhoff's White Christmas

"Man I gotta take a shit but someone is on the only shitter!"

"Guess you'll have to do a tandem mudslide"

Tandem Mudslide by gangster_hops October 14, 2009

tandem hunting 

A couple, typically a male and female, who search together for threesome partners, usually another female.

My friend and his girlfriend usually go tandem hunting in nightclubs for bi-sexual women.

tandem hunting by Neo-Rio October 20, 2007

tandem fap 

When two or more people masturbate at the same time.

When I walked into the room RJ and Adam were tandem fapping to pictures of my mom again.

tandem fap by Shanus teh Anus January 28, 2008

Tandem poo

We two people poo into one receptical simultaneously.

Me and my girlfriend just had our first tandem poo. It was more emotional then sex.

Tandem poo by the grumpy nipple doctor March 11, 2012