My first ever OT in IBM

My first ever OT in IBM.... After working for 3 months, I finally had my first taste of OT. Oh man, I stayed till 8pm to complete my work. It was quite an experience. The office become quieter and quieter. The aircon seems stronger and the place feels colder as more and more people has left the place. Good thing my neighbour was still around so we could still chit chat.

Anyway, when IBMers (that's how IBM employees are called) work after 8pm, they are entitled to claim dinner and taxi fare. And usually they verify us working late by looking at the time reflected on the taxi receipt. Hmm, how would I be able to claim OT when I walk home. What can I used to verify that I stayed back late. Any ideas?