The lost-and-found office at the world's top beer fest really has seen it all when it comes to eight million beers downed each year at the Oktoberfest.
A total of 4,900 items were lost at last year's festival, with the objects missing ranging from the sublime to the ridiculous.
Alongside 1,220 items of clothing, 420 mobile phones, 380 pairs of glasses and 70 umbrellas, presumably well-refreshed party-goers also mislaid a megaphone, a dog, a viking helmet and five wedding rings.
"The problem is that people get drunk and only realise they've lost stuff the day after," he explained.
"As a lot of the people are tourists, they have already left and they can't get back to reclaim their things."
On the opening days of the festival, the intake is always meagre, he said, taking down the details of a dirndl-clad woman who had lost her mobile. Only a few dozen items were lost so far, but he expected the pace to pick up later.
"We've seen everything. People have lost wallets with thousands of euros (dollars), diamond engagement rings, all sorts of valuable stuff," said Mueller.
The most commonly lost items were keys, jackets, mobile phones and wallets, he explained.
In the same building, there is also an office for reclaiming children lost in the Oktoberfest crush, complete with toys to entertain the wayward kids while their parents are on their way.
"Last year we also had an abandoned wheelchair and two pairs of crutches so you have to wonder how those people got home," he laughed.
The wheelchair was later claimed by its owner but no one ever came back to pick up the crutches. "Maybe they were cured by the beer," joked Mueller.
Lost property is kept throughout the 16 days of the Oktoberfest. Items left unclaimed are moved to Munich's main lost-and-found office, from which Mueller and his team are seconded every year for the festival.
Objects lost by the millions of foreign visitors to the world's biggest folk festival are transferred to their respective embassies and consulates, said Mueller.
Mueller said that last year, he made a furry find before its owner even knew it was lost.
A dog belonging to a businessman at a nearby firm wandered onto the fairgrounds, hoping to lap up some tasty treats.
The canine festival-goer was eventually delivered to Mueller, who rang the number on the dog's collar to tell the owner the good news.
"'Don't be silly, he's under the table,' insisted the owner, before realising that in fact the dog was missing.
The grateful but slightly sheepish businessman came to collect his pet an hour later, Mueller recalled with a chuckle.
This year's Oktoberfest runs until October 7.