Enthusiastic agreement can be expressed in many ways, such as the four-letter word 'AMEN', the six-letter words 'Illsay' and 'Yesyes'. 'AMEN' is a Hebrew word meaning 'so be it' or 'TRULY', and is often used to express agreement or acceptance of an idea. 'Illsay' is a slang term derived from the phrase 'I'll say', which is used to express agreement or enthusiasm. Finally, 'Yesyes' is another slang term used to express enthusiastic agreement.