A small amount of knowledge can cause people to think they are more expert than they really are.eg. he said he'd done a course on home electrics, but when he tried to mend my table lamp, he fused all the lights! I think a little learning is a dangerous thing
If something is an accident waiting to happen, there's definitely going to be an accident or it's bound to go wrong.
('Disaster waiting to happen' is also used.)
Similar to ahead of the pack, ahead of the curve literally refers to your position on the statistical bell curve, where the top of the curve represents the median, average result. By being ahead of the curve you represent the top percentile of results that either has the advanced skills or understanding that sets you apart.
If you air your dirty laundry in public, you reveal aspects of your private life that should really remain private, by telling a secret, arguing in public, etc.
If something has all mod cons, it has all the best and most desirable features. It is an abbreviation of 'modern convenience' that was used in house adverts.
(UK) An idiom that appears to have gone out of use but was prevalent in the English north Midlands of Staffordshire, Cheshire and Derbyshire from at least the turn of the 20th century until the early 1950s or so. The idiom's meaning is literally something said or written that is unbelievable, rumor, over embellished, the result of malicious village gossip etc.
(USA) If you have been all over Hell's half acre, you have been traveling and visiting many more places than originally intended, usually because you were unsuccessful in finding what you were looking for.
It can also be used to mean everywhere.
(USA) Used in response to someone saying "almost" in a win/lose situation. The full expression is "Almost only counts in horseshoes and hand grenades." An alternate form puts "and flinging shit from a shovel" at the end.
If someone is always a bridesmaid, never a bride, they never manage to fulfill their ambition- they get close, but never manage the recognition, etc, they crave.