A "Felly Welly" is an evolution or a new stage of "Felly" used for a new nickname or name in general, having many stages and forms and is able to go on forever and more with new names rhyming with "Felly" including "elly" in it to give justice and remembrance to the first stage of this evolution.
"Hey Felly Welly, how are you?"
"Shut the fuck up Felly Welly"
"Hey Felly Welly shall we give you a new name?"
"You're gay Felly Welly."
"Felly Welly is the Felliest Felly doing the Welliest of Wellying!"
Dammit, I was sucking on a huge new cock last night. Everything was perfect, except I was a little bit drunk, and I broke wind right in the middle of it all. Thank god he was drunk too, and we made a joke and called it mufflered fellatio. We had great sex, but I was pretty embarrassed.