Gross! I would kidnap it and first spray it with lysol then find out who he's been talking to.
You should beat him to the chase...mwaha, call him secretly in the morning before anyone else can. First, make an excuse why you won't be home and be outside near the house when you call. Then, start a long conversation with him--he will be so surprised! Do this at the exact time he goes to the bathroom in the morning!
Another thing you can do is hide his cellphone.
Another thing you could do is, while he is asleep, take a bunch of pictures of random bs and fill up the simcard so that he can't receive any text messages. Also, leave a bunch of voicemails calling and hanging up so that he can't get anymore voicemails, lol(you probly won't take it that far though)
you could have so much fun with this!