I was waiting in a long basket-only queue at the supermarket with a massive basket of goods when I looked back and there was a girl standing behind me with a bottle of juice. I was just about to reach the till, so I said "Do you wanna jump in front?", to which she was surprised and said thanks, moving in front. As she did so, I noticed a middle-aged lady behind her had only two items, so I said the same to her. She replied "Oh wow, I don't get offers like that since I was her age - I was just thinking 'I bet he did that because she is young and pretty', so thank you, that's very kind".
I always do this for men and women alike, so I just laughed and said 'no, it's just I'm overloading my basket and feel a bit rude to keep you guys waiting'. They both looked at me and were clearly only 80% convinced (it turns out she was very pretty). So I blushed at this point, realising how it looked.
I thought to myself "well, I know I do, so that's all that matters" and just kind of stood there looking awkward. As the girl left I glanced up at her at the same time as she shot a look back to say "Ha! I caught you! So much for chivalry", and I must have looked shocked and confused because she then gave me a lovely knowing smile that made my day.
This story is from Quora.