The story
From you ain't heard nothing yet, a phrase originally popularized by Al Jolson.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: There's more where that came from; what you have seen so far is only the beginning. Used to inform the listener that they should expect further surprises, and that the speaker has only just begun doing something. Full definition →
From you ain't heard nothing yet, a phrase originally popularized by Al Jolson.
Etymology from Wiktionary, CC BY-SA 4.0.