There used to be, and maybe still is, a Spanish tapas bar, in a basement on Charlotte Street, which claimed to be one of the oldest in London. It stayed opened very late so we would nip down there after work, certainly after licensing hours, and get silly. One of its house specialities, which should give you a sense of the depravity of this establishment, was a Depth Charge, although perhaps it was just the depravity of our crew.
Take a large sherry schooner, fill it with Tia Maria and lower it into an empty pint glass. Slowly pour draught lager down the side of the glass until full. The heavier liqueur will remain in the schooner. Sup the lager from said pint until, at some point, the schooner will tip over and you are obliged to down the contents, all of a sudden, in one go, through the depths of the beer.
The effect was uplifting but not an elegant business to recommended to clients in any classy cocktail establishment if you don’t have a mop handy. It could end in more than tears.