Either:
A ride to somewhere for which no payment is demanded.
Or
an easy time; participation without contributing anything.
It's not an idiom - ships once had to ride the tide out of harbors because they didn't have motors and had to rely on the tide and the wind to carry them along.
This is a gambling idiom. If you let something ride, you leave it as it is or let it stand. The image is of you leaving your bet on the table instead of taking the money or changing your bet.
If you can offer a solution, you are encouraged to try.
The full idiom is "Free things can be very expensive". An idiom is a turn of phrase that seems to mean nothing, but requires thought to unravel. The reason free things can be expensive, is that they're generally free because they're not very useful.
If you think about this, you can figure it out. A roller coaster is a fast, scary ride. If something is like a roller coaster ride, it would be a very busy experience that is fun, but also slightly scary.
On the house means it's free, or that the person who says that will pay for whatever you got.
It means you do not have to pay for dinner,either it is free or someone else will pay for you. This idiom usually means the 'house' or restaurant owner will pay for not 'anyone'.
That's when someone goes somewhere with someone else or a group of people despite not being enthusiastic about the destination.
RFP is not an idiom. It's an abbreviation.
It's not really an idiom. It means "what are you thinking about."
It is not an idiom, it means your nose is itching.
means you don't have to pay for that service