These are some things in German that I hear often around here. I'm sure I'll add more as I learn more German and recognize more words.
Alles klar = all is clear, or "I get it"
Geil = cool. Be careful with this one; it can also mean "randy."
Ja, ja = yes, yes.
Ach so = I see. Ach kind of sounds like "ah." I hear this one a lot and it usually stands alone in a sentence when the listener is confirming that she understands what the speaker just said.
Nä = no, used instead of or in addition to nein. It's a regional thing I've been told and it sounds like "nay."
and the top one...
Genau = exactly; you're right. Goodness! I feel like I'm being genaued to death around here. People say it ALL THE TIME.