Tags that should imply "covering", and a few to alias

covering breasts, covering nipples, covering crotch imply-> covering
 
covering vagina, covered crotch alias-> covering crotch
 
Maybe:  
covering nipples alias-> covering breasts  
hiding erection imply-> covering (because it seems to be used equally as much for “trying unsuccessfully” as it is for proper covering)

“Hiding erection” is a bit inconsistent so I’ll leave that off for now, but the rest done.