The first months Bardroy is at the manor not only does he very quickly pick up a British Accent, but going out to drink constantly on trips to town when allowed (though frowned upon to do so much) leads to him slinging around all the British slang and curses at the time.
Both Sebastian and Mey Rin are especially the ones ruffled by this. (see what I did there wink)
And soon Bard's hard earned pay is disappearing and also Sebastian is becoming extra aggressively bossy.
The day comes when Finny is even asking him about some of these phrases "Mr. Sebastian never taught Mey and I those!! ...Though I have a feelin' Mey knows what they are but won't answer my questions about it.."
Suddenly Sebastian is there to keep him from saying more or Bard from answering, and the rest of that day is very touchy for the chef...