Foster The People to do free Soda Bar show tonight, after Mattress Firm Amphitheatre concert with Paramore

“Let’s Get Small” was the name of a Steve Martin comedy routine in the 1970s that poked fun at pot smokers. But don’t tell that to the Los Angeles band Foster The People, which is about to get small — in a literal, if quite different, sense — at the Soda Bar in San Diego’s City Heights neighborhood.

After appearing tonight, Thursday, in Chula Vista at the nearly 20,000-capacity Mattress Firm Amphitheatre tonight with Paramore, FTP will head to the 230-capacity Soda Bar to play a free show. Admission to their 21-and-up performance will be on a first-come, first serve basis.

The Soda Bar gig is part of FTP’s “Sacred Hearts Club” Punk Rock After Party series of free shows, which began after last year’s release of the band’s third album, “Sacred Hearts Club.” Two young San Diego bands, Almost Monday and Ignant Benches, will open FTP’s Soda Bar show tonight.

In the words of FTP, their Punk Rock After Party enables the group “to take over a local dive bar/club after their (major venue) show to create a free pop-up event with local music, a ‘70s punk DIY atmosphere, and a rock and roll party by the band.”

Best known for its 2010 breakthrough hit, “Pumped Up Kicks,” FTP will assume a different musical persona at the Soda Bar. While the band will include some of its own songs, expect the focus to be at least as much on FTP’s covers of such punk and post-punk classics as the Ramones’ “Blitzkrieg Bop” and Joy Division’s “Transmission.”

The free admission policy is designed to provide an option for FTP fans who can’t attend the band’s major venue shows. Previous FTP Punk Rock After Parties have also featured a food truck, a tattoo artist and a silk screen artist.

Will that be the case in San Diego?

“Not at the moment, but that might change — still hammering out all the details,” said Soda Bar honcho Cory Stier, via email earlier this week.

There will be no wrist bands or physical tickets for tonight’s free FTP show, Stier noted, and “people can begin lining up whenever they’d like, no restrictions.” After the club reaches full capacity, entry to the Soda Bar will only be if someone leaves first.

Foster The People, with Almost Monday and Ignant Benches

When: 9 p.m. tonight, Thursday, July 19

Where: Soda Bar, 3615 El Cajon Blvd., City Heights

Admission: Free (first come, first served); must be 21 or older to be admitted

Phone: (619) 255-7224

Online: sodabarmusic.com

george.varga@sduniontribune.com

Twitter @georgevarga