There are people who giveaway bitcoins if the user can solve a quest. Think of it as a treasure hunt, or solving a riddle. It usually involves finding the seed phrase on a picture, which actually holds the bitcoin.
It also usually involves the holder of the quest proving that he actually holds the bitcoin. This is done by signing a cryptographic proof, which includes the bitcoin address the funds are held at, a custom message, and the actual cryptographic signature. You can verify this by going on site like: URL