I feel like it's pretty obvious he said "Check out the big brains on Brett", but in a "stylized" and dragged-out way. The amount of conspiracy theories on this is absolutely insane lol. I think Tarantino is truly a genius in filmmaking, but to insinuate that this small detail that even closed captioning disagrees with is because of a kid of a friend he had is lowkey crazy. I saw this thing the other day on TikTok (I know lol) about how if Americans say the letters "R N R", it sounds like an Australian saying "Oh no". But just because it may sound like you're saying "Oh no", it doesn't mean you are actually saying it lol. Maybe it's a bad analogy (I've been told I'm not very good at them), but it's the best I could come up with. Anyway, Samuel L Jackson just really exaggerated the way he said "Brett". That's it.