Okay, I'll start...
You jump onto a floor light, thinking you'll be sent to another time.
You wonder why you can't cast Luminaire on your little brother/sister.
You refer to your girlfriend as Marle/Lucca/Ayla
You think that Lavos will destroy the world in 2012
You try to use your mobile phone (Mammon Machine) to absorb energy from a jagged rock (Lavos), thinking that you will become immortal.
You get a free-range egg and a doll that looks exactly like your dead pet and take them to the top of a hill, thinking that you will revive the dead pet.

When countless of times players try to add Schala into the party but fail. I'm still try to add Schala in my party. I'm convinced that she's a possible character, really .

You wonder why the koala in the zoo can't teach you magic.
You add 'Nu' to the end of all your sentences.
If somebody annoys you, you shine a torch in their eyes and shout LUMINAIRE!
You pour wine on a gravestone, expecting the dead person's soul to come up.