submarine sex 

Sex of submarines

Wow they're having submarine sex

submarine sex by Submarine Sex April 3, 2019

Silent Submarine Sex

The act of performing a sexual act while one or more people are in the same room.
Usual occurs at drunken parties and gatherings.

Dude, I Silent Submarine Sexed Sarah last week after you passed out on the couch,
or
Me and Sarah had Silent Submarine Sex on the floor while you guys were playing monopoly.

Silent Submarine Sex by Jordo.. March 16, 2006

I sexually identify as a submarine 

For those who sexually identify as submarines

I sexually identify as a submarine! Respect my periscope you bigot!
Shoot your torpedo inside me USS Wahoo (SS-238)

I sexually identify as a submarine by lord of the silver rings June 2, 2017