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.