Hi please help.
A. Well, at least it is just a coffee. I have had worse things spilled on me.
B. No, seriously. I feel terrible. Let me buy you a new shirt or something?
A. That's very generous, but I think I will survive.
B. No, I insist. I owe you at least a coffee, right.
A.okay okay. How about this : you buy me a coffee, and I will call it even?
What's " I owe you at least" in this sentence?