G: I think I can reconstruct what he meant. Crown Royal itself isn't the peanut-butter thing. Crown's current flavored lineup includes apple, vanilla, peach, salted caramel, blackberry, chocolate, etc., but not peanut butter. citeturn0search0turn0search6

The likely bottle he named was Skrewball Peanut Butter Whiskey—easy to hear or remember as something like “peanut-butter Scotch.” Skrewball is specifically a peanut-butter-flavored whiskey. citeturn0news36turn0search5

So there are two plausible drinks depending on exactly what he said:

Crown Royal + Red Bull is absolutely a known combination. One published version is actually 1:1 Crown and Red Bull, while another uses 1 shot Crown to half a can of Red Bull. citeturn0search8turn0search9
Skrewball + Red Bull is probably what you're describing if you're certain he mentioned peanut butter. That's a stranger combination, but I can see why somebody would say “weirdly, this isn't bad.” Peanut butter gives you sweet/roasted/salty flavors against Red Bull's sweet-tart fruitiness.

If the problem was “good, but too strong”

I'd not simply add more Red Bull first. That will weaken the alcohol concentration, but it also pushes the drink increasingly toward Red Bull and adds more caffeine/sweetness.

Instead, I'd try:

1½ oz Skrewball + 3 oz Red Bull + 1½–2 oz club soda, over plenty of ice.

The soda water is doing exactly what you want: lowering the alcohol intensity without introducing another major flavor. The carbonation also fits naturally with the Red Bull.

If that's still too whiskey-forward, go to 1 oz Skrewball + 3 oz Red Bull + 2 oz club soda. At that point you've substantially reduced the alcoholic punch while retaining enough peanut-butter whiskey for it to remain an identifiable part of the drink.

There is one other option I'd actually be curious about: cold brew coffee. Something like Skrewball + Red Bull + a small amount of cold brew could make conceptual sense—peanut butter/coffee with Red Bull's fruitiness—but now we're deliberately changing the flavor rather than merely cutting it.

One caution worth mentioning: Red Bull doesn't make the alcohol itself less impairing; caffeine can make someone feel less sedated while they're still impaired. So club soda is especially useful here because you're reducing the amount of alcohol per glass without needing additional energy drink.

And appropriately: 薄(うす)める means “to dilute / make weaker.” That's pretty much exactly the operation you're after here. memcite