Whenever I deal with a maze-like spellcard, I mutter "Kagome, Kagome" to myself as reference to Flandre.
When I fight Orin, I like to quote Reimu's "the cat turned into a cat" line.
During my last playthrough of DDC as Sakuya, I often said "along with my typical maid duties, I also kill for a living..." as reference to her more psychotic lines during conversations.
When I finally unlocked the extra stage in EoSD, I just laughed like a lunatic (pun intended).
When my brother listened to me read the dialogue in SA, he asked me if someone bought Hell during the conversation with Yuugi.
I like to yell "everybody chill out/calm down" during moments when there are a lot of enemies as reference to TheAnimeMan's first try of PCB.