Guys, My male friend keeps flirting with me but when I say look I'm not dumb I know you like me he clams up. Wth?

Ok first off I normally don't go on sites looking for advice. But I have this male friend who is 5 years younger than me and we met at work. We started hanging out after I left the job and he flirts all the time with me. I brought it up to his attention and he clams up. For example we went out one night and he would grab my waist from behind twice (no reason to) he even said out of the blue that night if he offered himself up to me I would probably say yes. I'd say we have a very healthy friendship nothing sexual we go places and do things together all the time. But today I finally said to him look I'm not dumb I know you like me and he clams up and changes the subject. Then later on he says he is flirtatious however I've seen him with his friends and he doesn't flirt like he does to me and he doesn't grab them like he says he has. But it took him forever to come up with an answer. I just need males input on this bs.

Guys, My male friend keeps flirting with me but when I say look I'm not dumb I know you like me he clams up. Wth?
Post Opinion