From the author's README on Thunderstore

11 random cosmetics. Some of them are even good!

1- BAOH Baggy Cargo Pants 2- Doug Jones Tight Crop Top 3- GlorpShirt 4- OBC Icon Hoodie in Navy Blue 5- OBC Icon Hoodie in Off White (with red accents) 6- Iron Chef French Loose Crop Top 7- It's My Birthday T-shirt 8- It's My Birthday Loose Crop Top 9- Mass Of Fermenting Dregs Iwaou Pants 10- Rambo 3 Dedication Camo Dad Cap 11- SCW WTHx3iaC3 Denim Sleeveless

Install Ominous Bird Clothes

You need ReSkate and your own copy of skate. on Steam.

Open ReSkateLauncher.exe and go to MODS.
Search for Ominous Bird Clothes and click install. The launcher also installs anything it depends on.
Press PLAY. In game, the MODS tab of the ReSkate menu (Insert) turns it on and off.

Or install it by hand: download the .zip and drop it on the launcher window, or unzip it into its own folder in Mods\ beside Skate.exe.

Maps show up in the ReSkate menu's level list. To join a server running a custom map, you need the same map installed. If the game won't load after installing, see known issues.

skatemods doesn't host or review this mod. The download comes straight from Thunderstore. Only install mods you trust, because scripts can run code.