Some bands rattle and hum. Others jangle and bite.

Don’t mistake Frightened Rabbit for some floppy-hatted folk band that’s got as much common-man grit as a box of Frosted Flakes. Neither should you think that they’re indie rock bros with matching haircuts and songs ready for a mayonnaise commercial. The righteously sour Glaswegian stalwarts — don’t forget, strong since their 2006 debut — pulsed with insistent rhythm and wondered how the Messiah got so famous, all during their Friday afternoon set at Austin City Limits Music Festival.

Frightened Rabbit.

Rousing rock, topics of impolite conversation. Burn your flower crown on the ground, because singer Scott Hutchinson is not here for it.

“Festivals for a pessimist like myself can be a depressing affair,” Hutchinson wryly confided to the Miller Lite stage crowd before calling out the casual attendees in their folding chairs. “Go get a beer and be obnoxious.”

It’s difficult to explain why Hutchinson gets away with being so caustic, except to say that a smile and a triumphant-sounding chorus go a long away. The insistent “Get Out” made a strong salvo at the start, thanks in part to explosive drums and guitar breaks that sound like an ancient spirit breaking free from a moss-covered castle. Yet Frightened Rabbit’s lyrics are always a brick to the head: “Get out of my heart/She won’t, she won’t.”

That was the Rabbit formula: Be a little salty about sacred cows and drive it home with the sounds of a swollen heart. An early-set performance of “Holy” was a pew-burner in more ways than one, as Hutchinson proclaimed his hole-filled imperfections amid pleas to be spared from New Testament brimstone warnings. And on “Head Rolls Off,” he declared that Jesus is “just a Spanish boy’s name.” Older cut “Keep Yourself Warm,” meanwhile, chastised those “looking for love in a hole” with the reminder that “it takes more than (expletive) someone you don’t know to keep warm.”

So you’re doing it wrong. All of you. Whoever you are. And it seems that Frightened Rabbit counts themselves among the hopelessly broken.

The claimed humilty in “Holy” aside, songs like “Living In Colour” drowned in a rapid fire vibration. These aren’t snotty punk songs or fist-raised protest rock or Bruce Springsteen. The band’s constant, unrelenting rhythms felt like a racing heart, or like a thought that you just can’t get out of your head. And yes, with just a streak of plaintive fear behind those lyrics about all that doubt.

What saved Frightened Rabbit from their own cynicism was just honest-to-goodness rock. Like a U2 you can have a beer with.