Call me boring, but I was quite happy with a friendly handshake and 'well done' form the CFI. Any cutting off of parts of my clothing would have seem a little 'naff' and childish.
Actually, I did get a certificate signed by the instructor which I nearly threw away. I'm glad I didn't now. My daughter (age 7) has it on her wall and tells her friends how clever her dad is. She seems genuinley proud, which is nice.