what to do in this situation

well im a situation i dont know what to do any advice??
what happen
a few months ago about january i bought this prepaid cell phone well for a couple of days i had it i put minutes on it well i got this calls from some body sayin the phone is stolen and then hung up well everything was going good then at school i heard this 1 guy sayin he wanted to buy a phone and i was like i dont use this anyway so i said 20 bucks its yours and he was like with the charger well i sell him the phone on about a thurs now the couple days things are coo he walks up to me hello my goood man ;yes he said this; and handshakes etc well like on wed he comes to me talkng about he put mins on it and some woman keeps takin the mins off can u do this? and hes like i want my money back then i was like well all you need is a chip i basically gave him the chip free bcuz a phone for 20.00 is a pretty good deal anyway it was a t mobile to go phone
well now its like a month or so later and every class hes been buggin about the money well he says all this shit talkin about i could pay installments im like wtf
should i refund him i dont kno if he tries to fight me well....his arms are long as hell but hes skinny so i dont know maybe if i get ahold any advice

is this situation my fault/? i dont know thanks any advice

Just stay cool. Don't let him intimidate you into doing anything. If he's talking about fighting you, don't worry about. Just brush him off, he made the choice of buying a phone. I've found that in every hairy experience I've been in, keeping my calm has saved me. Explain to him that he should call the company himself to solve HIS problem. His problems aren't yours. My advice to you is to not let it come down to fighting, not over a phone. Good luck.

btw hes been making threats since it happen so bluff?

I read that without taking a breath and my face turned blue.

tell him to call the company and to get off your ass

the phone is stolen stolen chip if he cllls company ....

wait, you bought a stolen prepaid phone, then re sold it? did you tell the guy it was stolen before you sold it to him? do you have any common sence? :)

i didnt know it was stolen at first...but all it need is a chip

dude, TELL him NOW that the reason the minutes keep coming off is because it's a stolen phone. If I were you, (well, I would never be in this situation, lol) I would give him his money back and tell him to ditch the phone, or get a new chip if you can?

he knows the phone is stolen