Straight(?) friend being confusing.. advice?

So one of my best friends, who knows I'm gay, was sending me some very mixed signals the other day.We were messaging each other when he all of a sudden, out of nowhere, told me he was very horny and hasn't had sex in ages. He told me he was wanking and wanted me to imagine it. He then mentioned wanting to experiment. I figured he was just joking by this point so I decided to call his bluff and told him it was making me really horny and that I was going to snap him a picture of my dick (he said he didn't want to send me one though). I just sent a blank snap, because I really couldn't tell if he was being serious and would have been super awks to send him a dick pic when he wasn't, but he opened it immediately and said was disappointed because he wanted to see.Shortly after this, I asked if he was being serious about the experimentation. He said no but it was nice to know that I'm interested.Before this exchange there was literally 0 thoughts in my mind about him being gay (or not totally straight (and have never thought about him sexually before then).Like wtf? What do you think us going on in his mind? Is he just screwing with me or should I have actually sent him a dick pic?I'm really worried about catching feelings for another straight guy so should I just shut them down now? Do you think it's worth pursuing?Btw we're both 20, and he's literally one of the biggest fuckboys I know (hence why I'm so confused).Thank you!