75th 

Short for the 75th Ranger Regiment, or 75th Airborne-Ranger Regiment. The 75th Rangers are an elite Army Ranger unit capable of being deployed to any point on the face of the Earth, kind of like the SEAL's, but specializing in conventional warfare.

"There are a LOT more Ranger regiments than this one."
-me

75th by Dave November 1, 2004

75th base 

When you turn on xbox live and stick your penis through the disc tray, your partner ther sticks their vagina the other side and you have incercourse whilst your dick is being cut on the Halo 3 disc you left in the Xbox.

Terry: Hey Sam I totally got to 75th base last night
Sam: Seariously? .. You're messed up man.

75th base by Perak September 2, 2009