Tunnel-buddy 

When two gay men share a chronic addiction to anal fornication. Habituation of anal sex will eventually scar one's anus, marking one as a permanent "Tunnel-buddy."

"Oi, faggot, I heard you were officially labeled as a Tunnel-buddy by Anderson Cooper."

Tunnel-buddy by xingm8y May 5, 2014

Double tunnel buddy 

When you and your bro have both taken down the same chick via both tunnels (vaginally and anally).

“Bro! Are you my double tunnel buddy?”

“Don’t even tell me you double tunneled with that Lindsay chick, bro”

Double tunnel buddy by BuffyTheManSlayer September 16, 2018

Bluetooth Tunnel Buddy 

If your friend has a girlfriend, and his girlfriend slept with his sister, and you sleep with his sister. you are now Bluetooth Tunnel Buddies with your friend

hey you know my buddy matt? I am his Bluetooth Tunnel Buddy

Bluetooth Tunnel Buddy by florida stanley February 20, 2020

tunnelbuddy

slang - Homosexual man (i.e. the catcher)

That over there is walking like he's got something up his ass, he's got to be a tunnelbuddy

tunnelbuddy by Tom Thamuz September 1, 2003