Cheerful, for suspicious reasons...

referring sexual actions and/or alcoholic beverages

is an adjective that is used to describe those who are fucking idiots, and are entirely oblivious to this fact. Especially pertaining to those who ramble on and on about things that are clearly only relevant or interesting to them. Therefore, everything that comes out of their mouth is comparable to that of a chirping bird or in other words, no need to listen.

A rare disease caused when a female has intercourse with a chicken, than proceeds to import the males anatomy (the penis) into a part of her body, this than exports the male seamen (jizzle). After entering the vaginal area the seamen combines with the chicken fertilization and forms together in the process of pregnancy. This has a 96.55% chance to cause the child to have the disease known as "Chirpies." Cherpies have many effects on children such as, outbreaks of chicken pox in your genital areas, urges to have gay butt sex, molesting little children, and beastality. Allthough there is no cure for cherpies you can prevent it before it happens by seeing your doctor if you suspect urges to have sex with chickens.

A true definition is a Jerboan Greeting for everyone.

When you chirp so hard you make the birds around you scared to chirp.

A very cheerful student who makes a room all brightened up