A phrase that you use whenever you're quite unsure of whether it would happen or it wouldn't, yet you need an answer for a person who ask you about an event in which the circumstances are still unclear
thus using the term "shi maybe" as a way of saying ' could happen could not we'll see'
A: Yo you going out to the party tonight ?
B: I can't, I gotta do my homework
A: Can't you just skip it for this one ?
B: Shi Maybe