Sports
hit a home run
to be successful
butter someone up
to be extra nice to someone (usually for selfish reasons)
the elephant in the room
The big issue, the problem people are avoiding
take a rain check
to postpone (delay) a plan
come rain or shine
No matter what
a ballpark figure
an estimate or guess
sell like hot cakes
bought by many people
once in a blue moon
rarely
a perfect storm
the worst possible situation
burn bridges
Destroy relationships
to fail
cheesy
silly
get a taste of your own medicine
Get treated the way you've been treating others (negative)
(to be) under the weather
feeling sick
sitting on the fence
can't make up his/her mind; can't decide or make a decision
drop the ball
to miss an opportunity
the best thing since sliced bread
A really good invention/idea
beat around the bush
Avoid saying what you mean, usually because it is uncomfortable
on cloud nine
the ship has sailed
It's too late
blind sided
unable to see something coming
don't cry over spilled milk
There's no point to being upset over something that has already happened and cannot be changed.
speak of the devil
The person you are just talking about shows up
raining cats and dogs
raining hard
you can lead a horse to water, but you can't make him drink
You can't force someone to make the right decision