Flimbo can not spawn in game but it is in the game files as some sort of admin climbonian.
Flimbo has lore to it, And heres the lore (Confirmed by stickbug). Flimbo was originally a baby fredrick, seen in fredrick's horrible fate, It says that It was going to find it's father (Fredrick was the father who abandoned it) Then it gets dropped in a strange black void, There appears to big a giant mouth behind it, And that was how Flimbo Was Born! He punishes sinners, for all actions have consequences