This behavior is usually caused because the French people have always been able to adapt, and rarely have the politeness to ask an English fellow to speak French in the presence of a majority. This leads to strange results when the French begin to speak to other French fellows in English, resulting in poor accent and dialogues.
A single English person in an entire group is enough to cause this behavior.
- Pourquoi tu me parle en anglais?!
- Ah, excuse moi..."
- "I think I'm struck with the Abraham Lincoln Syndrom.
- Hey man, I'm french, so talk to me in French!"