What would you do?

I got this email from a friend.

Something bizarre happened to me on Monday - I was propositioned with a lime - a whole one and yes, a fresh one too! Maybe it wasn't meant for me...who knows but basically, someone had slipped a lime into my luggage (while I was sitting at the other end of the carriage) and upon closer inspection, there was a name, number and message written on it. I don't know if it was a fellow passenger or someone walking around Paddington Station (or working there) who followed me onto the train. It makes me wonder that had I had a suitcase with a lock, what would they have done?!
I had a hold-all with no lock, by the way.

So what would you do? Would you call him? I am curious to find out what on earth possessed him to do this and why a lime??? What would you say?

I thought such a novel approach deserved a reply. So I advised her to call him but to do it from a phone box or dial 141 before dialing from home so he wouldn't get her number (just in case it was a weirdo).
She decided on a text message, and we were very disappointed to find out it was a couple of teenage twats having a laugh.