It's often used to emphasize the intensity or significance of something, like:
* "He left the job sti mpampa" (He left the job with a bang) - meaning he left abruptly or dramatically.
* "We celebrated his birthday sti mpampa" (We celebrated his birthday in a big way) - meaning they had a big, lively party.
The "mpampa" part comes from the sound of a loud bang, while "sti" is a preposition meaning "with".
While it's not a formal or literary phrase, it's commonly used in casual conversation to add emphasis and color to expressions.