"Grease the palm" is a commonly used idiomatic expression used to refer to bribing or tipping someone in a clandestine manner. The phrase is used to describe the act of paying someone off or providing a monetary incentive for them to do something illegal or unethical. Some synonyms for "grease the palm" include "bribe", "corrupt", "payoff", "kickback", "sweetener", and "inducement". These terms are often used interchangeably, but it is important to note that each carries its own nuances and connotations. Regardless of the term used, the act of "greasing palms" is universally frowned upon and illegal in most countries.