"For the Love of Lena" will see 10 men compete for the grand prize, or prizes ... as the case is here. Some of the contestants include TikToker Cripmac, tap-dancing virgin Cherdley, male porn star John Legendary -- who's known for banging other men's wives -- and "dreamboat" Thugger.

Expect some stiff competition when the show launches Monday on YouTube -- but the eventual champ's threesome with Lena and Adam -- their first male-male-female -- will be on OnlyFans. Sorry, no freebies for the steamy, and very adult, finale.

Adam and Lena are no strangers to making headlines for their unconventional marriage -- you'll recall he became the butt of jokes earlier this year when he fully consented to male porn star Jason Luv sleeping with his wife.

Lena passionately defended his honor, telling us it was a double standard because they had hundreds of threesomes with other women and no one took issue with that.

If you didn't know, the couple's been doing their successful "Plug Talk Podcast" for years ... where they interview a random woman before hooking up with her. Now, they're on to bigger things, leveling the playing field with the reality competition.