Rocking one's shit is a term used when someone is looking particularly attractive. Usually when they're wearing something that makes them feel or seem more attractive. However, it can be used for someone who simply looks uncharacteristicly good by some random unintentional force
Forms of "Rocking One's Shit":
"I totally feel like I'm rocking my shit today."
is totally rocking her shit! Did you see that outfit?"
"That guy is SO picky. You need to seriously rock your shit if you want a chance with him."