Years ago I bought a Burberry raincoat in Limerick, where it was considerably less expensive than it was in the US. Rather than travel with it, a friend said he could ship it, cheap. Okay.
It arrived a few weeks after I did, really rumpled, and without a duty. It also had a note in it, taking me to task for "forgetting to clean out all my clobber when I left". Customs, obviously believing I was simply absentminded, cleared it through. Maybe your gear could include a note apologizing for inadvertently snagging it when your friend packed, or thanking you for the loan of it?
My Aunt and Uncle used to visit from Canada every summer. My aunt would buy sheets and things here, and would remind my mother that she shouldn't make up the bed in advance. Customs never wanted to dig through the dirty laundry to see what might have been relatively new. My uncle was always having to change his shoes as well, so they would be worn before they crossed the border. It was our annual joke.
All that said, I brought some Belleek china to my cousin in Toronto, and paid through the nose for customs at the airport. Those folks were positively humourless.
