No monkey business at this urinal please

 

As seen at Riverstone Brewing Company, Eagle River WI, 7/31/2024

According to Merriam-Webster, the first-known use of 'monkey business' , as in SHENANIGAN (i.e., tricky or questionable practice or conduct), occurred in 1835.

Other coinages from the same year include:

1. athleticism
2. barman
3. decurved
4. growing point
5. unconventional