Maybe others have flouted the shirt rule and you never knew. That may be the source of the shirts. Maybe it is a superstitious way to “show interest/the love” to the colleges he really cares about?
My DD20 is not doing anything particularly strange but she is hesitant to do independent research on schools which is not her usual approach to things. She has been tasked with identifying at least two more schools by 7/15. I reminded her Wednesday of the list DH and I provided her as a starting point. She did get started on it but I was a bit surprised that she is not further along in her research. Maybe focusing on the schools she has already identified is her way of motivating herself.