Many excellent possibilities. Explicits tend to stand out more than incipits. I’ll name two of my favorites. The first from yet another novel I read in 8th grade (and the first time an explicit really stuck with me):
Johnny Tremain by Esther Forbes:
True, Rab had died. Hundreds would die, but not the thing they died for. ‘A man can stand up.’
And maybe one of the greatest (and most discussed) of all time:
Invisible Man by Ralph Ellison:
And it is this which frightens me: Who knows but that, on the lower frequencies, I speak for you?