Yu-Gi-Oh!
Yu-Gi-Oh! is a Japanese multimedia franchise and internet subculture. The franchise is known for its usage of cards.
Background
Nico Nico Douga fads
When referring to Yu-Gi-Oh! on Nico Nico Nico Douga, the series mostly includes only Yu-Gi-Oh! Duel Monsters, Yu-Gi-Oh! GX, and Yu-Gi-Oh! 5D's.
For Yu-Gi-Oh! Duel Monsters, the episodes 121, 129, 159, and 162 are the most notable on Nico Nico Douga.
For Yu-Gi-Oh! GX, the episode 34, is the most notable on Nico Nico Douga.
全速前進だ! (Zenzoku zenshin da!) is a line from Seto Kaiba from Yu-Gi-Oh! Duel Monsters, that garnered attention on Nico Nico Douga from episode 121. Another fad by Seto Kaiba, and to a lesser extent Katsuya Jonouchi, is the usage of the Enemy Controller Spell Card, and its button inputs.
ドロー!!モンスターカード!!! (Dorō!! Monsutākādo!!!) is a line from Yami Yugi from Yu-Gi-Oh! Duel Monsters, that is notable for being in one of the first publicly uploaded videos on Nico Nico Douga from episode 162; of Yami Yugi using the Berserker Soul card. Another line from episode 162 from Yami Yugi is "HA☆NA☆SE".
強靭!無敵!最強!/粉砕!玉砕!大喝采! (Kyōjin! Muteki! Saikyō!/Funsai! Gyokusai! Daikatsusai!) are lines from Kaibaman, the series, Yu-Gi-Oh! GX, comes from episode 34.
Songs in Nico Nico Douga medleys
Songs from the anime and films used in Yu-Gi-Oh! videos are commonly used in medleys.
More info about Yu-Gi-Oh!
See Yugipedia: https://yugipedia.org/