Oil of angels American old-fashioned
It can also be phrased as "oil of man".
Money that you give to someone so that they will do something for you, usually something dishonest.
They gave the waiter some oil of angels to find them a better table.
They should not have been allowed over the border, but somehow they managed to give the guards some oil of angels.
He discovered that certain corrupt officials had been given some oil of angels to approve shoddy construction work.
The word "angels" is used in the plural form by default.
The phrase "oil of angels" came to mean bribes in the late 16th Century, when "oil" didn't refer to the ubiquitous material it does today.
You try or experience something such as a new job, activity, etc. so that you become more familiar with it.
I worked as a teaching assistant for two months, just to get my feet wet.