In the air use the d pad for emotes. That count as tricks. Left is a can-can, up is no hands, right is a can-can and down is a superman seat grab. Easier than trying to flip.

JunorJ is offering the helpful comment, first need one of the "trick" sparrows equipped as JunoJ outlined, then emotes become tricks in mid-air. If you do it with the other sparrows you'll just start pointing out landmarks for your fellow racers. Also, the trick sparrows can roll or tumble when you hold down the R trigger, complete a full roll or flip and that also counts as a plus 1 to the 10. But the "up" emote is the easiest to pull off without rolling yourself off the track ;)

Do you have one of the new fancy sparrows, ev-30 tumbler, or swift driver? It says in the instructions when viewing a sparrow if it can flip.

Everytime you're mid air, hit one of the emote buttons. Good luck.