I brush at the sink. Otherwise, I'd be stepping out to spit into the sink and rinse and I'd be all cold and dripping everywhere... it sounds so unappealing to me lol.
Can't you just put on a bathrobe and go to the sink while the conditioner soaks in? No need to get unsanitary in a place where you're supposed to clean up, like you shouldn't combine all those gems where you're going to be naked.