Has anyone worn other teams colours?

I remember when I was starting secondary school, the dress code for PE was white top, white shorts and trainers.

Parents being parents went out and bought all my kit.

But when I opened up kit bag to find my mum had got me some white Aston Villa shorts as it was the only white shorts she could find I was mortified to say the least!

Have any of you worn another team colours either through no fault of your own or have you been made too?