Don't ask me, because I have no idea.
Rob over at Off the Post sent me this link to the shirt.
I have no idea what it means, and googling "Freddie Ljungberg + Hamster" is no help. I'm thinking it's probably some deep, existential, philosophical thing, related to the futility of the modern sports business/industry.
Either that or it's some kind of urban legend I'd rather not know about. (See: Gere, Ricard + gerbil.) (Or on second thought, don't.)
Either way, I found the shirt kind of amusing, and it's almost the team color, too. Except that the poison green needs a little more...poison.