The red party cups that are often present at high school and college parties where alcohol is being served. Nobody ever knows exactly what drink is inside the cup, giving the reds their sketchiness.
Bro #1: Yo I was at that party last night, sketch reds everywhere. Put my cup down and I didn't know if I got roofied or what.
Bro #2: Yeah man, gotta watch out for those sketch reds. Never know what you're gonna get.