Expression: Avoir les chevilles qui enflent
Pronunciation: [ah vwar lay sheu veey kee a(n)fl]
Meaning: to have a swelled/swollen head, to be full of oneself, too big for one's britches
Literal translation: to have swelled/swollen ankles
Notes: The French expression avoir les chevilles qui enflent is informal and insulting - you use it when you think another person thinks too highly of himself or herself. This is one case where I think the English expression is better. One's ego is in one's head, so it makes sense that being very egotistical would mean a person had a big head. In French, though, you think a lot of yourself and your ankles swell... where's the logic in that? :-)
Odile pense qu'elle va gagner ? Elle a les chevilles qui enflent.
Odile thinks she's going to win? She's full of herself.
Synonymous expression: avoir la grosse tête - literally, "to have the big head"