Not really good french from me but is "emm er deux" which sounds similar to "a merde"

Emm Err Deux

Nah, it actually sounds more like 'emmerdeur'

https://en.wiktionary.org/wiki/emmerder

A bit of trivia, there's a radio that is called NRJ which sounds like 'énergie' when you say it (in French)

Nobody, to my mind's got this quite right yet so I'll give it a bash...:

MR2 = Ehm Air Duh ~~ Merde :) cuz the middle e is like the ai in air (near enough) and the last e is like the uh in duh (near enough) - Not a native speaker so caveat enunciator

It sounds like "Eh merdeux", which in French means "hey filthy" in a bad way, "un merdeux" is someone who's covered in shit.