Today I went to a very-well known fast food drive through and ordered my meal. At the paying window I was told that the car in front of me had paid the six dollars for my meal. Accepting this kind gesture, I asked how much the order was for the car behind me. It was over $30.00. Being a broke student I had to pass on paying it forward but I still feel a little guilty for not having continued the kindness. AITA for this?