"I do bail on you"

What's this suppose to mean? HELP! thanks :)

ASAP please

What is the context?

If the context has to do with jails, arrests, etc., then it would mean "I will post a bail bond so that you can get out of custody prior to your conviction and sentencing."

Another possibility is that it refers to abandoning another person, especially at a time of great need. The word "bail" in that case would come from "to bail out" (to exit an airplane in an emergency by using a parachute).

to bail on (someone) = dejar abandonado (generalmente a ultima hora)
dejar plantada/o.

pero ojo! porque on bail también es "bajo fianza"

Como dice Thomas, depende del contexto. Contanos de qué se trata.
Saludos