Red vs. Blue: Reconstruction, the new character Wash doesn't swear much. So in his final moment, when hearing a computer terminal use the word emp (when he had been repeatedly telling everyone is pronounced "E-M-P"), he basically goes out with his final line being:
Wash: Emp? You have got to be fucking jo-
Sheila/FILSS is a soft-spoken, well-mannered AI whose voice never registers an emotion other than helpful politeness. When she does swear, it's always in the exact same tone of voice—and it is always hilarious.
The machinima "Beans", a crossover of 3 separate Super Smash Bros.. Brawl series, has one of these. The character Super64, a character from a series where nearly no one cusses at all, utters "Both of you, shut the FUCK up!!" to get 2 of the other characters to stop arguing and focus on the task at hand. Both of them (who happen to use the Cluster F-Bomb quite a bit, including in this moment) immediately stop arguing and stare at him in disbelief over what they had just heard