Yes, people like you lose stuff at a Jamboree. Yes, lots & lots & lots of stuff. So, you don't want to be embarrassed by a display of lost underwear in your campsite? Then write your name & unit number on everything.
Yes, everything. All personal items, including clothing, should be marked with your Jamboree Unit Number and name for easy identification.
A quote from a Jamboree-experienced Venturer Scout:
Return any found items to the Jamboree Support Centre.
LABEL LABEL LABEL ITEMS!!!
Trust in the force.