There are a number of beer cocktails. Famous ones are Black and Tan or half and half which is essentially stout and pale ale or lager mixed together.
I have no idea if there is a name for the one I did the other week. My only defence was, I did not make it. The American I was drinking with got the beers. He was trying to re-create a beer cocktail he had back in the US. It turns out the type of Kriek available was wrong, I'm guessing it was too sweet. We tried different variations like half and half and so on to mostly stout with a little Kriek on the top.
It was not a very good experience but I did drink most of it. The Kriek left over was drunk by my wife when she arrived later.
A shandy is the one I am most used to. That is simply a half pint or so of lager (doesn't matter which) and the rest is lemonade (like sprite or 7up).
It may be an abomination to serious beer drinkers but it is very refreshing and allows you to have a full pint and still drive. Though many sneaky Irish pubs charge you for the full pint.