Image from Mos Burger.
The "Choux Pot Shake" sounds like it would be a great name for a dance. Perhaps some wordplay could even be used such that one stuck a foot in a flower pot and attempted to shake it off a la "shoe pot shake". Okay, maybe not so much, but it'd be very entertaining for bystanders to watch a bunch of people on the disco floor pantomime trying to dislodge a stuck pot from their foot.
This type of choux is the French kind rather than the type that you shod your feet with and such desserts have been popular in Japan for a very long time. You can buy simple ones with either whipped cream, custard or a mixture of both in most convenience stores and markets. For something with such an upscale feel, it is decidedly common and available as a mass market item. I used to buy a tray with 9-12 tiny little one-bite ones at Lawson 100 (for 100 yen/$1.03, of course) on occasion so I could nosh on one without having to cram one of the giant ones into my cakehole.
Since they are so common, it's no surprise that a fast food place like Mos Burger would get in on the gig. For 380 yen ($3.90), you get a mug lined with choux pastry with custard and either a vanilla, coffee or strawberry shake. It's on the expensive side, but you do get to keep the coffee cup (and don't we all need more coffee cups) as well as have the sense that you're a cut above the ignorant rabble with their plain old shakes in paper cups, sucking at their dessert through a straw like a plebeian.
If you'd like to set your computer up like a plebeian, Mos Burger has wallpapers for you here.