Burdock

When I was a kid we used to play with these each year, throwing them at each other, and trying to stick as many as possible on as many different items of clothing as we could.  I think we used to call them stickybacks.

As an adult, (occasionally) I will try and attach a few to my loved ones unbeknownst to them. Just as I will try and attach a clothes peg to a loved one without them knowing.