Nah, this isn’t official St. Olaf gear.
Found one of these after talking to some students at St. Olaf College last week. They said some Ole student started selling them a while back, and that campus administration really frowned on them. (I’ve got a call in to officials there.)
They also said Carleton has its own shirt for St. Olaf:
Northfield Community College
(Heh! Johnnies and Tommies might take note.)
Update: St. Olaf spokesman David Gonnerman called the shirts “juvenile and disrespectful,” but said he didn’t believe they’d been banned.