This is actually a mangling of the two Japanese words kage and hoo. Kage is the word for shadow, while hoo is the word that is used in place of phoenix (when in reality its actually the Japanese firebird of legend). So the word "kageho" is actually a bastardization of Japanese words that is supposed to mean "shadow phoenix". More or less was used to "sound cool".
"I like how your pet kageho looks today."