MC Double Def DP
Rapper whose painfully awkward flow is the highlight of the Software & Information Industry Association's famously bad anti-piracy video Don't Copy that Floppy (1992) and Don't Copy That 2 (2009). The leading light of the "Yay for intellectual property" school of hip-hop, Double Def DP appears on a library Mac LC to chastise two kids for thinking about making illegal copies of The Oregon Trail and Tetris.
In the sequel, his vaguely updated rhymes accompany video of families getting arrested because their kids pirated, apparently,Doom. (A video game released the year after the first one was produced, which makes it about the same age as the target audience of the PSA.) Then he dances with Klingons. In both appearances he's played by M. E. Hart, who is also a lawyer, interestingly enough.
Oh, and get your minds out of the gutter; "DP" stands for "Digital Protector."