UNWANTED dick pic HELP!

So a few weeks ago, a random account on Snapchat started messaging me, saying he was a guy who went to a high school not far from where I live. (I'm a 16 year old girl) Then he started talking about how he had been 'dared' to send a dick pic and the next thing I knew he sent one! I was honestly so grossed out. I told him that what he did was disgusting especially since I didn't even ask for it, and then immediately blocked him. Well, the exact same account just did the exact same thing to my friend! This is so inappropriate and I'm really upset but is there anything I can do about it? I wish he'd stop doing it because I'm sure he's doing it to other people. If anyone has advice please help me

Edit: I'm not saying anything other than I think what he did is immature and completely unnecessary. If my friend or I wanted a dick pic we would have asked!