So my nephew (12) is coming up for his birthday at the end of this month to play his first ever DnD game. My friend is DMing and is asking for character ideas. Seeing as it’s nephew’s first game I want to make it enjoyable and hopefully funny. It’s Fifth Edition.
I was thinking of playing some kind of do-gooding paladin who is incredibly charismatic but otherwise pretty dim and incompetent, but I wonder if anyone else here has hilarious characters they think could be worth trying 
Hie thee to ENWorld.
For my own part, how about a ‘Tim Nice But Dim’ estate agent (realtor) type?
I have no input for the character idea but I have a suggestion, Do not make him go through character creation, just give him something already made and fully ready to roll. (HAH I said ready to roll) Get his input about what he would like to try but then have the GM roll something up for him.
It helps new players to not have to sit through all that tediousness before they ever even get to play.
Be sure to give him a deep and abiding love of mushrooms.
There are no mechanical ways to do “hilarious” builds or anything like that at 1st level. Everything is very straightforward.
The only way to make a bad character in 5th edition is to try. Just ask him what he wants to play, use the quick-generation in the class description, and go nuts with the roleplaying.
But let him pick what kind of character he’s going to play. That’s the whole point.
Well, the OP said he “was thinking of playing some kind of do-gooding paladin who is incredibly charismatic but otherwise pretty dim and incompetent” – so I say he’s not a paladin at all, but a mundane fighter by way of Navin Johnson: an orphaned elf raised by humans, who never got taught a cantrip but somehow just knows one anyway.
So he charges into battle, and ANGELIC MUSIC PLAYS: he has his own theme song, and it’s A HEAVENLY CHOIR! At that, when he lifts his grimy sword to the heavens, it just all of a sudden GLEAMS! And his shield bears no emblem, until HOLY SYMBOL!
He believes he was chosen by the gods to do good. He wasn’t, but so what?
We just ran a DnD 5e character creation session the other day, and it was a bit of a pain. It’s not nearly as simplified as I had been led to believe, mainly because there’s not always a good explanation of what you’re choosing (for example, it’ll just say “choose 2 of these 5 possible skills” without explaining what skills are and how they’re useful).
The recommended order in the player manual is also race -> class -> background, which is a bit backwards, since background can allow for some choices that would affect what you choose in your class selection. For example, I was making a Dwarf Paladin, and chose Acolyte as the background… well, Paladin gets to choose 2 of 6 possible skills, but then two of those same skills are automatically awarded to the Acolyte background, so you’ll need to go back and re-choose skills to avoid overlap.
Figuring out all the numbers like AC and saving throws and spells and etc are all much easier with an app, as well.
So yeah, anyways, I would ask your nephew for a general idea on what he wants to play, maybe throw out some general ideas on race/class/background then do the legwork of creating it from there.
Reading back I see that I misread. I thought you were creating a character for your nephew to play, not thinking of one for yourself. Me culpa.
Here is the primary 5e chargen spreadsheet: Forged Anvil.