These cups were used in Costa Rica, during one of McDonalds' Sonic promotions. However, the toys came with kids' meals, but these are the "Big Size" type cups. Did the larger meals also come with something else Sonic? Fortunatly, someone thought to collect them all! Photo credit to: mAtt Pieper A.K.A. Sonictoast. 

As you can see, Sonic, Tails & Knuckles were featured on paper (midsize) or plastic (large) cups.