Shirt Swapping

Memento: an object that you keep to remember a person, place, or event
”I keep my match tickets as a memento.”

Etiquette: the set of rules or customs that control accepted behaviour in particular social groups or social situations
”Shirt-swapping comes with some unwritten rules and etiquette.”

Cherish: to love, protect, and care for someone or something that is important to you
”I cherish the match-worn shirt I was given by a player.”