Oftentimes people learn inappropriate or slang words first. One of the things that intrigued me most about Japanese was that this was NOT the case in my situation.
The first phrase I learned in Japanese (aside from words such as "hi", "bye", "thank you", etc.) was "taisho umakattayo" -- "master, how delicious!" This intrigued me, and I knew I wanted to learn more.
What was the first phrase that you learned in another language?