It's unclear what the man was doing wearing the hood, whether he was protesting the wearing of masks for COVID-19, or whether he thought he was being funny. The store manager, the clerks, and eventually the mayor of San Diego weren't laughing though.

Source: LA Times

SANTEE — A man was spotted wearing a Ku Klux Klan hood in a Vons in the San Diego County city of Santee on Saturday, igniting outrage from the mayor, the head of the Anti-Defamation League in San Diego and others.
A corporate spokeswoman said grocery clerks repeatedly asked the shopper to remove the hood or leave the store, located on Mission Gorge Road.

A supervisor found the man once he was in a checkout line and asked him again to take off the hood or leave, said Melissa Hill, a spokeswoman for Vons, Albertsons and Pavilions stores in Southern California.

The man removed the hood, purchased his items and left.