My crush sent me a picture of his butt?

Musicale
Sorry, this is kind of a weird question. I'm in high school and I've been talking to this guy for about two weeks. I feel like we have good chemistry, and I actually feel really comfortable around him, which is highly unusual when I have a crush on someone. He's been sharing all kinds of things, especially about his family and his plans for college and a job, and he really seems to care about what I have to say.

So after these sweet, totally clean interactions I was surprised when he sent me a picture over snap chat of his butt (he was wearing clothes) and I had no idea of how to respond or why he sent it. I didn't send him any pictures like that of myself, just a normal snap chat, and then he sent me a sad face? It kind of just hit me that maybe he wanted me to send him something dirty? (Something I would never do)

People often tell me I'm shy and innocent, while my crush is a bit of a flirt and has been with girls in the past. (Although we do have a lot of other things in common) I told my best friend, and she thinks he's bad news, but she's never said a word to him. So I'm just confused. Do you have any explanation as to why he would send this picture? Would you send a picture like this to a crush if you were interested in a relationship? And do you think I should keep pursuing this? I like him a lot :/ but I don't want him to use me.
My crush sent me a picture of his butt?
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