Thank You Sir

"Thank you, sir."

When I was on the high speed rail train yesterday, I found myself very thirsty. Standing in front of the vending machine, I did have enough coins. I was wondering if there's anyone who I can exchange some coins, but that was just a thought. Walking on the way back to my seat, I felt much more thirsty (probably by the fact that I did not get a drink). So whimsically I randomly asked a two boys, both looked like about 20, whether I could exchange some coins. They said they didn't have ones. Feeling a tinge of embarrassment, I turned a man beside and asked the same question again. He took out some coins with his hand upward to me, but there wasn't enough for a hundred dollar bill. For a second, I wished I can disappear from that atmosphere. I told him I have hundred dollar bill only. To my surprise, he said "It's alright! Just take thirty dollars. Here you go!" Then he gave the coins as the way my dad would do. Though feeling uncertained, I took them and brought a bottle of water. Before I would walked by him again, I stood there and looked through my bag trying to find anything I could give to him as a thank you gift, but I can't find one. Finally I just said "Thank you, sir!"
, and I guessed that's the best feedback one would like to hear.