Two men allegedly hurled abuse at patrons of a city centre McDonald's before one of them indecently exposed himself, police say.
ACT Policing are seeking witnesses to the incident, which occurred between midnight and 1.30am on Wednesday at the McDonald's on Cooyong Street.
Constable Rosemary Catton described the alleged actions of the two men as "offensive".
"We know that a number of people were affected by the offensive behaviour of the two men and we'd like them to come forward and contact ACT Policing," she said.
"Even if you weren't affected or offended by the behaviour we are urging people who witnessed the incident to come forward.
"One of the identified victims in this matter is a vulnerable person and any information could assist police with the investigation."
Police described one of the men as a bald Caucasian, around 180 centimetres tall, wearing a black jumper, navy tracksuit pants and sandals with socks.
The other was a thin Caucasian, 180 cm tall, with short dark hair and a trimmed beard, wearing a blue jumper and camouflage-print pants.
Anyone with information on the incident is asked to contact ACT Policing on 131 444, quoting reference number 6092545.