The Jenner sisters were in suburban Sydney to promote their clothing line and hundreds of fans were there to meet them ... including one pissed off older woman.
Police tell us the 30-year-old was perched on a higher floor of the mall when she hurled several eggs down at Kylie and Kendall. The eggs hit the stage, and splattered on some fans ... but the sisters dodged the yolk.
Cops spotted the woman and arrested her for offensive behavior. During the bust, police say she spit on one of the officers -- so, she was also booked for assault.