Ask her if she minds if you take a shower, then if she lets you, ask her if she'd care to join you. Personally, i would leave out the part about "you stink" since you probably are sweaty too. She may be thinking the same thing. This way you both get to clean up and have some "fun" scrubing each other in all those nice places. Alot of fun can be had during a nice shower, so there are other benefits besides the freshening up part of it.