A passenger who had the words "I am gay" written on his luggage with airline baggage stickers believes the incident happened at Perth Airport.
Jetstar Airways has reportedly apologised to the Queensland man and said an investigation was underway.
A picture of the bag was posted on Twitter on Saturday and by this morning had been reTweeted more than 160 times.
User Sleepysaurus Rex!@aaronpp, who writes a blog under the name One Sleepy Dad, tweeted the photo with the caption: "Utterly disgusted to find my luggage front and center on the @JetstarAirways luggage carousel looking like this."
Identifying himself as a stay-at-home dad, the man told followers he believed the incident happened at Perth Airport during a weekend visit.
The man travelled from Perth to Brisbane.
"It's the luggage sticker tags for the flight. Add passenger #privacy to you concerns," he Tweeted.
Twitter users attacked Jetstar, describing the incident as "disgusting and unforgivable".
"We are taking this matter very seriously and we have contacted the passenger to apologise for any distress caused," a Jetstar spokeswoman said in a statement.