Alles hat ein Ende, nur die Wurst hat zwei - Everything has an end, only a sausage has two
Schwamm drüber - dont worry about it (literally means "sponge about it")
salonfähig - socially acceptable (literally "salon-ready, salon-worthy)
Fremdscham - vicarious cringe/embarassment
Fernweh - away-sickness (opposite of homesickness, which German has too - Heimweh)
verschlimmbessern - to make something worse in a genuine attempt to improve it
Leitmotiv is also a good one