If it's a large company follow the internal procedures outlined in order to deal with it.
If it's a small locally owned real estate don't engage in sexual contact - It could turn messy if he starts to want an actual relationship and you're only wanting casual. - He'll get jealous, You'll fight at work. You'll end up unhappy and ultimatly you'll leave or be fired.
The best way to deal with it is to approach him and just tell him it makes you feel uncomfortable.
