The realization that you're no longer 18 years old can come years after your 19th birthday and hit you like a ton of bricks (or VCRs, as the case may be). Over at AskReddit, people are sharing the stories of when they first realized that, damn, they had gotten old somehow. Warning: reading this might prompt some self-realizations.

1. The Back to the Future problem.

2. "No, tell me: who loves orange soda?"

Sources: Reddit