"Froggy's" is the local bar/hangout where, in Episode 5 "(The Game"),
Rebecca gets to sing on stage before the game,



...and where Jack & Rebecca go to watch the Steelers in the 1980 Superbowl.



During that game, the couple gets into an argument about having children,
Jack punches out a guy who complains about their noisy arguing...



...and, ironically, they later  accidentally conceive the triplets
in Froggy's restroom, while having make-up sex.


  
This is a real bar, but it's not called "Froggy's".

In real life, it's Godmother's Saloon.
You'll find it at 302 W. 7th Street, in San Pedro, CA.

(That's at the southwest corner of 7th & Centre Streets, down by
the L.A. Harbor, at the southernmost end of Los Angeles.)



The bar features a definite nautical decor, with the walls full of
ship's wheels, carved figureheads, mounted marlins, and the like.

And yes, it does indeed have a stage for singers & bands,
so there's a lot of live music on a regular basis.

Here is a photo of Godmother's real-life interior:




Here is a Google StreetView of the bar:



I was familiar with Godmother's Saloon long before this show.
It's a popular filming location, and I first ran across it when
it turned up in Season 3 of Dexter as  the "Blue Room" bar.

And since then it also showed up in Rosewood.

(You'll find their Facebook page here.)

The actual locations where TV's "This is Us" was shot.