A cool, re-usable plastic cup!
This cup is made by Party City in 2017. It has CG Sonic on a blue checker background, with big red slogan "Come On Step it Up!". This isn't really a 'party supply' though, it could be thought of as maybe a type of favor, but because it's not typical, it appears here on housewares instead. These light-weight but fairly durable cups have been around for other cartoon brands for quite a long time, but this one's a first for Sonic. These are typically about a dollar, if you can find them in stores. (If not, order it off the PartyCity.com website today! (A drinking cup, pencil cup, or just cool decor, a Sonic thing for a dollar is always a good deal)