A pseudo language created by german people who think they are cool and modern, they form english-looking words. This is often used in marketing. Germans can guess what it means, also it seems more new and innovative than real english/german words.
"DEnglish" is the combination of "d(eutsch) english". The term is mostly used by germans who are critical about the newly invented words.
Handy Flatrate - tariff/plan with unlimited time for calls (=flatrate) for a mobile phone (=handy)