to get to 4th base is to have anal sex.
"I got to 4th base last night with jenna"
"oh so you had anal sex with jenna?"
"yep, that's what 4th base means"
When you die trying to get to 4th base.
Guy: Hey dude! I hear you got to -4th base last night!!....
TO FUCK LIKE A DOG !!!! when u tell someone you got to 4th base they are very proud
i told my dad i got to 4th base with my gf he gave me a pat on the back
When a woman gives you a blowjob,see 3rd base, however doesn't allow you to cum and then proceeds to have sexual intercourse with you(4th base). Once again, she comes to the point when you are almost about to ejaculate, and then hops off and leaves you. Also see blue balls
Milton: FUCK MAN, my balls hurt so bad!
Milton: This bitch I was fuckin' yesterday got me to 3.5th base. I'm so pissed off.
Aziz: Oh dudeLOL, that sucksLOL.
When you get to home base twice in one evening, then have a threesome with said two previous people.
Danny seduced two separate chicks, man! Then got to play with them together! Holy crap, he's the first in our college to get to 10th base! We must worship him.
The act of having sexual intercourse with everyone on the planet... at the same time, whilst watching an episode of the hit comedy 'friends'
It is also not unusual to grow several detachable penises after u get to the one millionth and one base.
Richard: Dude i got to the 1000000th base last week!
Paul: What! that means you had sex with me! and my mum?! and my dad!!! you fucker!!!! What friends episode were you watching?
to go to 4th base with a different woman (or man) in all 50 states.
You:50! I finally did 50th base!
Partner: I thought this was fourth base!
You: it is for you, but not for me!