In men's clothes, I'm a:
XL for shirts.
XXL in bibfronts.
Size 10 shoe.
I can't tell you what size football helmet, but hubby is 6' 2", and his head fits his body. (Not bigger than average, nor smaller.) My CPAP mask is the same size as his -- medium. (My nose is bigger than his. Yes, we spend ample time figuring out the really minor stuff of life. lol)
(I can get women's clothes for what goes under and women's nightgowns, so I have no idea how men's sizes work for those kinds of things, but I like to think my bra size would be smaller, if they dared to wear a bra. lol)
And the average size teddy bear is 12". Mine is 18".
And, the teddy bear has footsie pajamas I made for him, but it's a two piece, not a onesie. (I'd love to make them all onsies, alas, I'm not good with buttonholes or zippers.) But, hey? Are you impressed? He's wearing a pair of pants I made for him. (Shirt is store-bought.) He has a tail stub, so pants are are to form fit on him. (Over a dozen stuffed animals down here with us in our living room, and each one has winter, summer, and Philadelphia Eagle season clothes. Their wardrobe occupies the bottom drawer in my chest of drawers and is spilling over into other piles in the bedroom. My theory is, if I'm hot or cold, so are they, so they must be clothed.)
(Or, short answer. I'm as nuts as you fear. lol)