One of the restaurant's most popular traditions is that patrons are required to hand over a shoe as deposit when purchasing one of these beers. This 8.4% Belgian Kwak beer is served in it's traditional round-bottom glass that by accounts is pretty darn expensive to replace, hence the clever shoe-deposit!
SheyMouse
I have not been there, but there is apparently a pub in Brussels which takes your shoe, putts it in a large basket with the others and hoists it to the ceiling. Apparently this has been going on for some time.
The Kwak beer is one of my favourites. Not a drink-till-you-fall-over beer, but a good sipping beer on a lovely evening.