You're carrying a travel of fast food and a drink to a table, when someone walks by and knocks your drink over, spilling everything. You're about to say 'Hey! WTF!', when the guy says "Pay it forward". What do you do?
You go back to the counter to get a replacement drink, only to be told that there is no free refills. You'll have to purchase a whole new drink. You're pissed and about to complain when this girl in line pays for your drink. You're about to thank her when she says "Just pay it forward". What do you do?