Meet the Mantis, a new a vehicle/mech in Halo 4. Your best Spartan soldier can get in it, step on enemies and, when he or she has them down, commence with the teabagging (you know, the, uh, victory crouches). It's all in the official trailer.
This is Microsoft knowing its Halo audience.
HALO 4: MANTIS TRAILER - Footage on Ragnarok [YouTube, upoaded by AirGuitar901]