Taking a shower while sweaty.
Sweating is the body's way of cooling itself. If you have already completed your exercise, showering would not cause ill effects. Sit around in your apartment stinking up the place. Actually, it's irrelevant. The sweat has already done it's job by cooling your body down. This might be hot to you, but cool to the parts of your body that perspired. If you need to run, go ahead and shower. it doesn't matter your body is gonna cool down while your in the shower. But it's best to shower after a long or hard workout mostly for skin reasons. Your sweat loaded with impurities that could cause pimples or other types of acne.
Preferrably, you can shower right after exercising because after exercising your pores are open.