Are you really serious - guessing this is a joke. If not then tell him to buy them himself - personally I would be uncomfortable with someone staying in my home asking me to buy them undewear and would contact AirBnB and ask them to cancel the reservation. Up to you...
Agree with @Gerry-And-Rashid0. Yuk! Ack! Rid yourself of this creep no matter how. Either that or sell him some of your used socks and underwear at a premium price. Hmmm...
i dont know if you're here just joking around with us... but that sounds really really strange.
If that guest have few reviews and would ask Airbnb to cancel the booking... i dont feel that's a "thing" you should ask to a host! What's next? "my bed is cold can you join me?"