Before I came to Japan in 1991, I took four years of Japanese at my alma mater, SDSU, so compared to most first-time gaijin I spoke quite a lot of Japanese. I could do many useful things, like ask directions when I got lost (which was a frequent occurrence, as there are no street names in Japan), and I knew just enough Japanese for me to put my foot in my mouth really, really well. Yes, I've committed many faux pas during my time in Japan, such as trying to impress a pretty girl by speaking Japanese to her, but accidentally using onna kotoba, words that women use which are the bane of male students of Japanese, or committing a deadly slip when ordering mango juice, since "mango" is dangerously close to the worst word that exists in Japanese. (Manko is the word for the female reproductive area.) In Japanese hospitals, thermometers are always used in the armpit, but I put one in my mouth, causing much shock among the nurses, who had never seen anyone do such a barbaric thing. And then there was the time I bought my wife some pretty flowers, only to find out that I'd accidentally bought kiku no hana (chrysanthemums), which are only used as offerings to the dead on special Buddhist days -- that really got a laugh out of her.
Very pretty, but only for dead people.