Natural News (AKA ramblingconspiracybullshit.com, thanks to A Dose of Buckley)
Neocities
Neoseeker
Polygon
The Porn Dude and its subsites
Puyo Nexus
Snafu Comics
Sonichu
TV Tropes
Twitter/X
Multimedia
Buffy the Vampire Slayer
creepy/gross porn
Cuphead
Cyanide and Happiness
Hatsune Miku
Hello Kitty
Homestuck/Hiveswap
Hot Wheels
IGN
InfoWars
Lego
Miss Kobayashi's Dragon Maid
My Little Pony (yes, really)
Neptunia
One Piece
Pop Team Epic/Poputepipikku
Rosario + Vampire
Scott Pilgrim
Sonic the Hedgehog
Steins;Gate
Touhou Project (moreso on the Western Hemisphere, ironically)
Transformers
Yu-Gi-Oh
Diet
advanced.gg
Burger King
Cheetos
Chick-fil-A
Coca-Cola
Domino's
Doritos
fruit snacks
Gamer Supps
G-FUEL
Hot Pockets
Jack Daniel's
KFC
McDonald's
Mountain Dew
Papa John's
Sheetz
Taco Bell
Wendy's
Conventions
Comic Con
MAGFest
MLP Cons
Momocon
PAX
Sonic Expo
Sonic Revolution
TooManyGames
Twitchcon
VidCon
Youmacon
Miscellaneous
autism
baseball/dad/snapback hats
beanie hats
black dot pupils/"Michael Myers eyes"
blank stares
BPD
completionism
Discord
disrespectful behavior
dog collars/"chokers"
Funko Pop figures
GiIvaSunner/SiIvaGunner
GitHub
Indiegogo
Infinite Craft
Kickstarter
ko-fi
*Linux
Neopets
NPD
OnlyFans
Ownaj dolls
Patreon
plaid clothes
red shirts
sexual ASMR
skulls
steam trains
subscription boxes
Telegram
Walmart
Youtooz
Keep in mind that merely liking children-aimed media does not make someone a manchild; Walt Disney even stated "Adults are kids grown-up, after all." Manchildishness usually combines specific interests with immature actions.