This one is most definitely NSFW, but I can throw together a family friendly version for you if you like. Subjects including but not limited to: Narwhals, Vampires, Rainbows, Hipsters, Gamers, Wild Attack Pigeons, Space Invaders, etc.
The size is pretty standard, but these can be made in just about any color. Convo me for special color/text requests! Also available in smaller size here: https://www.etsy.com/listing/89593799/the-original-warning-sign-pirates-and?ref=shop_home_active&ga_search_query=ninja
Have any questions? Contact the shop owner.