Thanks for all the comments.
I'm actually not trying to say languages should be static and we should all look in dusty old books for the "correct" usage. I just wanted to hear some opinions and see if anyone else out there finds the overusage of such slang annoying.
I think you could make a case for a lot of them and that's what I wanted to hear, such as 'checken' and all its variations. Some new meanings with their own connotations have come out of it, which has broadened the language, but stuff like releasen instead of freigeben is just done without any imagination at all, in my opinion.
@occo and anyone else who seems to be getting riled up:
Of course in English there's rucksack (which I never say, because I'm American) and angst (don't confuse it with fear though! angst: A feeling of anxiety or apprehension often accompanied by depression. Commonly used in teen angst). There's also zeitgeist, zeppelin, strudel, frankfurter/wiener, dachshund, schadenfreude, kindergarten, hamburger, gesundheit, hinterland, poltergeist, rottweiler, glockenspiel, doppelgänger, schmalz, gestalt, etc.
I'm all for them; they make the language richer. It just seems to me that in German it gets out of control sometimes. But, maybe you're right. Most of our foreign acquisitions in English came from French - which we then murdered and made them our own! So yeah, why not in German too? I'm sure the really stupid ones will eventually get weeded out through lack of use - that's the beautiful thing about language development. I guess being a native speaker of English makes some them harsher on my ears than others...
Worse than Denglish for me is the whole chat-speak that's developed: btw, omg, lol, etc. some are useful, others are just not my taste, like wuz for was... or over-using *lol*. Some people actually say some of them too!
@yx: you seem to have a really good handle on these. Do you think you can propose them to LEO? It would really help me out the next time I see some of these and have no idea what's meant. Usually I spend a lot of time googling until I get the gist. @wk auch.
'Checker' ist geil! I'm gonna have to throw that into the mix...