Sehnsucht (German) is the longing or yearning for something unachievable by someone, be it love or some of the motives common in the romanticism like travel and freedom.
1: Oh, sweet life why can't i be free and head out to and see the world.
Person A: Hey... I just got this old-fashioned TV the other day... Even if I never had one, I still feel nostalgia for it.
Person B: That's called Sehnsucht.
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.
FRIEND A: "Did you just take a stealthie of me?"
FRIEND B (turning phone around): "no I was just using snapchat's new filter, see?"