Waluigi was introduced by Nintendo in Mario Tennis in 2000 as Luigi's tall, scheming rival and Wario's doubles partner. His exaggerated voice lines, including enthusiastic shouts like oh yeah, became a defining part of the character across Mario Party, Mario Kart and other spin-off games. Because Waluigi rarely appears in mainline platformers, fans turned his catchphrases into memes celebrating the underdog. The short shout spread through gaming videos and soundboards as a compact reaction for victories, lucky moments and ironic self-congratulation.