I have just read Pussers book and it motivated me to jot down a few of the funnies I had experienced.

I was in a bar in Dune du Pyla with my lady friend of the time.  I was just starting to learn French and she insisted that I order the drinks.  I did this with a great deal of nervousness and hesitation but she immediately started pouring the correct drinks.  She placed these drinks in front of us and asked for the money.  I handed the correct money over plus a 2 Euro tip and said what I thought was “thank you very much”.  At this point her face went from a beautiful smile to a scowl and I could see she was about to verbally assault me.  My lady friend jumped in and explained that I was English and was trying to say “Thank you very much” not “Thank you nice arse”

mercy bow-coo is how it sounds to me.

merci beau cul and merci beaucoup both sound pretty much the same to me.