Much like the word enormous, Jon-normous refers to being larger than life either in size or other realms. Such as: being tall, large in stature or weight, having a large penis, high self-esteem, overly confident, borderline cocky. This word can only be used when referring to a person who has the name Jon or John, or any variation thereof. When named John, it's more appropriate to spell as John-normous.
Person can also be referred to as Big Jon or Big John.
That guy singing is Jon-normous! He's almost hitting the ceiling!
I'm kind of turned on by how Jon-normous he is. He is so sure of himself.