There is no such thing, and anybody who says this in my presence has, more or less, giving me license to knock their teeth in with a ball-peen hammer and rinse out the remaining broken shards of teeth with a mixture of raw lemon juice and salt.
Okay, that may have been a bit too harsh. But, a little history lesson for those that throw the term around so haphazardly.
Blackface performances and minstrel shows were performed across the United States and often used stereotypes that disparaged, humiliated, and dehumanized Black people in the country. One such performer, Thomas Rice, created and performed as a character in blackface known as “Jim Crow.” The character made him rich and famous, but the stereotypical character became synonymous with the term “Negro,” and politicians used Jim Crow as a symbol of populism against Blacks. These Jim Crow laws systematically made it a lot harder for an entire race of people to live life. The world was separated, and it stayed that way for over 100 years, from the time Blacks were freed from slavery to the latter third of the 20th century, and the effects and attitudes from those Jim Crow-era laws as well as those created in the minstrel shows that were a prominent part of society for much of that time are still felt in 21st century, which is shameful.
So, please, don’t call that show “nerd minstrel” or “nerd blackface” again nor even use those phrases in my presence. Otherwise, you’re having an appointment with a hammer.