not a joke

a customer walked in to the store...
leo : welcome to starbucks, mam. can i get you anything?
customer: yes, i would like to have latte for my boss.
leo : what size would you like your latte to be, mam?
customer: i am not sure what size he always have.
leo : ermm...
customer : well, do you know what size he always order?
leo : who's your boss?