The act of rubbing jizz in a circular motion on a person's forehead immediately after cumming on it with your index and middle fingers. Just as the blue-butted monkey did in the lion king after simba was born.
Guy #1: "Dude, that girl last night was so hot!"
Guy #2: "Haha, yeah she was until I Simba'd that ho."
This is when a woman has recently had a baby and her husband/boyfriend still wants to get it on. The woman is asked to perform oral sex to her man while still taking care of the baby. Thus the milkshake is the act of performing head while continuing to allow the newborn to suckle on her teet. Effectively making this a threesome including a man, woman and baby.
Att: Baby can not be older than 4 years old.
The baby is crying and I'm horny....it's time for a Kenyan Milkshake.