Babysitting A 14 Year Old !?

Last night I had the experience of babysitting a 14 year old while his parents are on vacation. He seemed like a normal 14 year old exept he's small for his age (4 foot 1) and 74 lbs. So at first everything was OK, but around 7 PM he was in his pajamas and he asked me if I could put a diaper on him and treat him like a baby. (I keep all sizes of diapers and onesies, pacifiers, etc in my bag) I'm 16 btw. So I said Why? He said because he really wants me to, and if I don't he'll say I hit him, and then I'll get fired, or he'll cry. So I put a size 6 huggies on him, and a large fitting onesie along with a bottle and a pacifier. He loved it, he crawled around and I laughed. but after he told me he went "poopie and peepee in his diapee" so I got out the power, diapers, wipes and changed him. It was actually a wierd experience. So do you think I should continue to do this everyday for him (2 weeks till his parents come home) or should I stop? is it bad? what should I do?