MK4 memories - Instantly falling in love with Tanya's and Reiko's endings.
MK Deadly Alliance memories - Nothing really, played it once at my sexy heterosexual friend his place, he touched my hands while learning me how to play it, it was romantic, for a sec...
MK Deception memories - Unlocking the characters with my little brother was fun, playing through that "story" mode was even more fun! Also I bought that game without knowing the roster at ALL, I screamed the entire day, OH NIGHTWOLF! oh JADE! ERMAC? REALLY!!!?? MILEENA? YEAH, BARAKA!!! SINDEL!!! It was like one long orgasm lol. Especially when I unlocked TANYA. Damn.
Mortal Kombat Armageddon was so bad, but I only remember seeing Rain's render (or whatever) and I was like, I NEED THAT GAME NOW! Other than that, it sucked and my memories aren't memorable, just horrible lol.
The other MK games were fun, but I don't have nostalgic memories about them, they are too recent.