fat
chew the fat (or rag) chat in a leisurely way, usually at length. informal
1986Tom ClancyRed StormRising Four-star admirals didn't chew the fat with newly frocked commanders unless they had nothing better to do.
fat cat a wealthy and powerful person, especially a businessman or politician. informal, derogatory
2013CNN transcripts Her parties … would be Nobel Prize winners and the top people in, who contributed to our society. It wasn't as it is today, a lot of fat cats and fund raisers.
the fat is in the fire something has been said or done that is about to cause trouble or anger.
☞ This expression refers to the sizzling and spitting caused by a spillage of cooking fat into an open flame. It was first used, in the mid 16th century, to indicate the complete failure of a plan or enterprise.
it isn't over till the fat lady sings: seelady.
live off (or on) the fat of the land have the best of everything.
☞ In Genesis 45:18, Pharaoh tells Joseph's brothers: 'ye shall eat the fat of the land'. Fat meaning 'the best part' or 'choicest produce' is now found only in this expression.