A piece of forbidden fruit has become an unexpected source of passenger outrage at Delta Airlines lounges: the banana.

Free food is part of the hospitality offered by airline lounges. While the buffet is complimentary, there are many unwritten rules for lounge patrons. A big one is passengers are not supposed to take food ‘to go’.

Many make a point of not offering bottled beverages to discourage passengers pocketing a couple for the road.

“All you can eat” and “help yourself” come with caveats to stop catering costs upsetting the airline beancounters. There have been outrageous examples of passengers bringing their own takeaway containers to the lounge buffet.

However, a recent altercation over a banana in Minneapolis Airport has led to pushback from passengers.

The Delta loyalty member says they were scolded for walking out of the lounge with a piece of fruit, according to a post on the Delta Airlines Reddit forum. A slip up that they say left a black mark on their record after they were reported by staff.

“Someone tell me this is all a nightmare and my $700 a year isn’t a complete waste. I just wanted a banana,” they said.

Bananas are the centre of a fruit-based protest at Delta Airlines lounges. Photo / Reddit r/Delta

The traveller texted their boyfriend distraught at the altercation. It seemed outrageous that Sky Club members - some of whom were paying $1495 a year - were made to feel like a criminal over a bit of fruit.

Unexpectedly this banana impasse has begun a movement among disgruntled travellers.

Many have taken to the web to share photos of fruit they say was looted from the Delta Lounge.

“I made sure they saw me take it,” read the caption of one selfie.

Others have found the “banana drama” hilarious, with bits of yellow fruit being left in unexpected places at Delta Lounges around the US.

One discovered a banana on the back of a bathroom stall.

A banana, allegedly lifted from a Delta Airlines lounge. Photo / Reddit r/Delta

Why Delta Airlines passengers are going bananas over this piece of fruit.

“What’s with all the Delta bananas?” read one caption, baffled by the fruit-based protest.

Another TikTok creator took the battle over the lounge buffet to another level, saying that bananas were small time.

She suggested going for the high-value meat platter, and smuggling slices of charcuterie in your keep cup.

“If you get 36 slices of salami per Delta sky club lounge visit, you break even on your annual fee after just 30.5 lounge visits,” she suggested.

The protests have come after Delta made changes to its lounge policies last month, making it more difficult for guests to visit and more expensive for members.

In February the airline quietly revoked access for some credit cards holders and reduced number of complimentary visits for others.