Why is he doing this? its just confusing!?

Okay I know I've asked this before but it just gets more confusing! So I'm 18, bi and well yeah I like this guy, I've liked him for a while and he is hot! First of all when I realised I liked him I just liked him been around and when I look at him he would look at me too and hold the stare and it would give me butterflies but see I don't know if he is definitely gay/bi he gets loads of women and just its confusing, but now everytime we talk it more flirty talking and joking with eachother and all! If I haven't seen him for a while and then I do I would see this big smile on his face! And I don't know I feel there something between us as in when we talk you can feel the tension! At a party we were both at was just me and him in the toilets and I said to him joking around, your gay! And he replied I know I am? And then it went on I was said "no but you really are" and then he got serious and said I am gay but I still dnt believe him! And then when were in a group he even said to my ex girlfriend that we hooked up me and him! Everyone laughs cause we know he's joking, but he just gives me that look! And then recently last week he was at my house (he's friends with my sister bf and my brother so he's always around) and it was just me and him on the sofa watchen tele when others where in the kitchen cooking, he said to me "I've got a present" and I laughed and said what is it and he opened up his trousers (not unbutton as in lifted then up from the waist) and said there it is look! So I got all flustered and blushed and he noticed and laughed at me! And I walked out of the room while he wa laughen at me, it was funny but he just gets even more flirty now! So recently I was thinking should I tell him I like him or play along and see how far it goes or is he just been like this cause he knows he can mess me around? He isn't camp and either am I we're just both average joes! So that's what makes it even confusing! But one night I nearly told him I liked him when I was drunk! So maybe he knows what I was going to say? I need help lol.. Give me some opinions or what I should do, and sorry for the massive book there, I'm the next 50 shades of grey! Hahaha.. Thanks!!