people only mentioned in one rap song ever

nevermind, meth got that one: "Even Grizzly Adams couldn't bear" XD

"Check it out yo, I smile like Groucho Marx"

- Fu-Schnickens feat. Shaq, "What's Up Doc?"

Opposite of this, people you would never have expected to be mentioned more than once, but are:

He was referenced by Richie Rich in Tupac Shakur's song "Rather Be Ya Nigga", in the line, "Smoke blunts, but leave them stunts up to Super Dave," in the Ice Cube song "Wicked", with the line "We'll have to break his ass up like Super Dave," in the A Tribe Called Quest song "The Chase, Part II" with the lyric, "We flippin' on niggas like we Super Dave," in the Cool Calm Pete song "Lost" with the line "You(r) fake stunts that's strictly for Super Dave". On Fat Joe's song "Bet Ya Man Can't (Triz)," Cuban Link raps, "We do maneuvers like Super Dave, always with a group of babes" and as well as in the line "At the hot tubs making a gang of waves, Hoe in the cunt doing stunts like Super Dave" in the song "She's Just A Freak" by The Luniz.

“hittin mothers and their daughters similar to Woody Allen”

not a person, but I always chuckle when I hear Kool Keith mention "Inside Herman's Head" on "One Two, One Two"

Obviously not the only song, but Big Daddy Kane was probably the first to mention Don Cheadle, shouting him out back in 1994

https://www.youtube.com/watch?v=95fAAsxcZzc

Went from the station straight to Orange Julius
I bought a hot dog from my man George Drakoulias
-Beastie Boys "Stop that train"

https://www.youtube.com/watch?v=nTWlVXDpg8c

"I make paintings based on grids just like Chuck Close" - MC Paul Barman