Lemonpopsicle (sic) is a term used to describe (generally) an older male who trawls internet chatrooms for young males to chat to/share inappropriate pictures with. The term originated from an undercover news reporter in the United Kingdom releasing details of the chatroom antics of a 48 year old man using the alias "Lemonpopsical". It has caught on as a local internet meme though is spreading slowly internationally.
A: Check out that user, he's been trying to get into that 16 year old guy!
B: Hah, sounds like he's a bit of a lemonpopsicle!