Like nobody’s business
Definition 1 of 1
Pro Tip 1/3Intensity Indicator
Use it to stress just how briskly or intensely someone is performing an action. 
The band was playing like nobody’s business, thrilling the crowd.
Pro Tip 2/3Informal Tone
It adds a casual tone, so it's not suitable for formal writing like academic essays. 
He started fixing up old cars like nobody’s business after retirement.
Pro Tip 3/3Hyperbolic Speech
The phrase is an exaggeration and not meant to be taken literally. 
When the sale started, shoppers began grabbing deals like nobody’s business.