Scooby-Doo! Behind the Scenes

Season 1, Episode 5: Velma, That Meddling Brain

Select Source

Velma chalks up her catchphrase, "Jinkies", to her simply being so surprised that it "just came out" and admits to having previously said the less catchy phrase, "Oh my!" A strong push from her parents to be successful academically is said to have resulted in Velma receiving hundreds of awards for outstanding achievement. However, it's this success that is blamed for her being "more vocal than her comrades would like".