Nothing about that was sarcastic. I learnt it off someone else when very young, and have been using it with certain family members ever since. When I recognised what you were doing, I was surprised and pleased. Heh.
Hah, interesting! This is the first time I've seen someone else replace the first letter of every word with a specific consonant (and 'b's the one I usually use as well), although it's simple enough that it should be fairly common.
I use it to communicate with other initiates when in Company.