Q:

catch the eco-friendly bug

In the French language, I'm searching for a natural way to say,

Hah, you've caught the eco-friendly bug or what!

My intention in saying this is to say that I was surprised to see someone who always purchases luxury cars having bought an environmentally-friendly car all of a sudden. I have no clue how I should say 'caught the eco-friendly bug.'

A:

I think there are various ways of conveying the surprise and the term.

Je vois que tu t'es mis à l'écologie
Je vois que tu as attrapé la fibre écologique
Je vois que tu as attrapé le virus écologique (using Con-gras-tue-les-chiens' answer)

As stated in the other answer, ecologique could be replaced by ecolo, conveying a slightly pejorative or mocking tone (and in Wallonia - Belgium - Ecolo is also the name of the "eco-friendly" political party)

A:

Qu'est-ce que tu as attrapé le virus écologique !

Or if you want to add a pejorative nuance to the tone of your phrasing:

Qu'est-ce que tu as attrapé le virus écolo!

