youth must have its fling; boys will be boys

therein lies the rub

(informal) every day, every blessed day

(figuratively) to be hasty, to get ahead of oneself

(informal) great, that's just what we needed; that takes the cake; that's the last thing we needed

(figuratively) to get a taste of one's own medicine; to have had it coming

nevertheless …; the fact remains that …

Alternative form of c'est en forgeant qu'on devient forgeron

the cure is worse than the disease

(figuratively) to be skin and bones (to be emaciated; to be very skinny)