I worked at Gamestop way back when so I never really had any crazy things to say (cause I generally know what I'm talking about lol). That said, some of the things my customers would say made me laugh and/or shake my head in embarrassment.
Example #1: Customer buys Halo 3 day 1 for Xbox 360, beats it in a week, comes back and asks for a refund since he beat the game. Customer is indignant when I tell him the best I can do is offer $40something as a trade-in. He wants the full $65.01 back because the game was too short.
Example #2: 8 year old boy comes in with his mom. He's looking at video games and pulls out God of War II for PS2. He brings it up to the counter and tells his mom to buy it. I tell his mom that there's graphic violence and nudity throughout the game. His mom responds with "oh he sees me naked all the time, no problem."
I'll try and post more as they come to me, it's been 10+ years lol