They still wear the heavy T-shirts with sewn-on letters although not necessarily in their own colors.

Okay, I know this is off-topic but since it was brought up--why is it that I see many fraternities/sororities wearing paraphanelia that is not in their organization's official colors? I've never seen a member of an ethnic greek letter organization do this, but I see it all the time with NPC and IFC organizations. Why is this?