If you send me to get you lunch and I pay for it, say $8, with my own money, you would reimburse me the $8. If you gave me an extra $1 for my trouble, you have compensated me.
Isn't that a bit of an artificial distinction? If the time it took for you to get his lunch is worth $1 then he's still simply reimbursing you for your incurred costs. Just because you left the situation with more currency than you started with doesn't mean you've made a profit.