It is a phrase said to intel a women has a big ass.
It also is a sly comment so the women would not know that you are commenting on her butt.
Ex:
*girl walks by*
Boy1: damn she got the booty dew
Boy2: Straight up bra
2👍 4👎
When sitting on a toilet for defecation and your buttocks completely seals the toilet the resulting seal causes a lack of airflow which results in condensation on the buttocks known as Booty Dew
Friend 1: I hate when i go to wipe after pooping and my hand get wet wit Booty dew
Friend 2: not the booty dew