I don't know about you, but to me there's hardly a thing in this world sexier than a man cleaning my grout with a toothbrush, unasked. Especially since it's "my job" to clean the bathtub.
(We each picked our least favorite chore and the other one does it. For me, I hate washing out ziplock bags so he always does it. He hates cleaning the bathtub, so I usually do it. We share all the other chores.)