Yeah, preferably Russian, Arabic or German - something with a lot of hard consonant sounds.
I have a coworker who I use as a test guinea pig for my jokes. (OK, I work third shift and I have only one coworker so I torture her.) We were having a bad night this past week and I said something similar to Yule's line here. I was talking about one of our patients but whatever. The coworker cracked up and I knew I had a good one. And I already know a bit of Spanish swear words. I have, at times, been known to string curse words together in amazing sentences that occasionally make sense.