The steel drums is a percussion musical instrument originating from the Caribbean region. They are played by "Pannists" using mallets. The steel drums can produce melodies, much like the marimba and unlike the drumset. The different notes are created by different steel thickness' in different regions of the drum.
In Advanced Safety Features, Frankie asks the group why they seem so interested in Troy Barnes. Jeff Winger seizes this opportunity to trick her by telling her that Troy was known for his ability to play steel drums. The rest of the group seems skeptical about Jeff's plan as Frankie leaves the room. Later, during the Alumni dance the group had been planning, Frankie joins the band Natalie Is Freezing on steel drums, and Jeff enjoys a pleasant "I told you so" moment.
In the next episode Intro to Recycled Cinema, Frankie and the steel drums make another appearance in the sci-fi bar.