The term 'EXTREMELY FUNNY' can be described by two crossword solutions: SIDESPLITTING (13 letters) and HILARIOUS (9 letters). Sidesplitting is an adjective that means so funny that it causes one to laugh uncontrollably. It is often used to describe a situation or joke that is particularly humorous. HILARIOUS is another adjective that is used to describe something that is extremely funny. It is often used to describe a situation or joke that is so funny that it causes one to laugh uncontrollably.