I'm looking up the translation for what the guy said before he slaps him. The last part means down with Macron but one of the translations for Montjoie Saint-Denis is "Hold the Line". I'm getting all emotional.
Hold the line yellow vest friends.
"Montjoie" has also been proposed as being derived from a Germanic source, mund gawi ("pile of stones"), supposedly used as a battle cry in a sense of "hold the line!". It has alternatively been proposed as deriving from mund galga, from mund "protect" and galga "cross, rood" (as pilgrims would often affix crucifixes to these stones).[5][6] Charles Arnould claimed the word originated in Gaulish mant- "path" and gauda "pile of stones".[7]
https://en.wikipedia.org/wiki/Montjoie_Saint_Denis!