Triple Triad in Final Fantasy VIII. I didn't have a PS1 back in the day, so I played it with my friend. We spent hours and HOURS trying to get all the cards...one of us would clap incessantly in the background whilst the other made a mess of it.

There was also a debacle involving the Ifrit SeeD trial in which my friend and I decided to make up a Shiva/Ifrit romance based on Ifrit's shocked exclamation of "They have Shiva?!" when we used her against him...I still shudder remembering what we came up with. It was even worse when we got the Brothers. We also made up our own lyrics to Fithos Lusec Wecos Vinosec because, of course, we had no idea what the hell they were singing.

...oh, and Rinoa's dog was cleverly re-named "My arse" for trouts and giggles. Because why use Angelo Cannon when you can use My Arse Cannon? Rinoa saying things like "My arse is really smart!" always got me too. Still gets me now actually, as bad as that probably sounds. xD

In short? FFVIII. That was what got me started. I doubt I would have had anywhere near as much fun if I'd played it by myself, though.