You've found the shop, but there are a couple of mentions of Jabberwocky Childrenswear in the 1968 and 1969 CDs in downtown LA. I wonder if they're connected. Both addresses appear to be offices: 110 E 9th Street and 746 S Los Angeles Street.
It might have got its name from "teenage jargon", but the origin must be the 1871 nonsense poem by Lewis Carroll, which added the words "galumphing" and "chortle" to the English language.
Jabberwocky
’Twas brillig, and the slithy toves
Did gyre and gimble in the wabe;
All mimsy were the borogoves,
And the mome raths outgrabe.
“Beware the Jabberwock, my son
The jaws that bite, the claws that catch!
Beware the Jubjub bird, and shun
The frumious Bandersnatch!”
He took his vorpal sword in hand;
Long time the manxome foe he sought—
So rested he by the Tumtum tree,
And stood awhile in thought.
And, as in uffish thought he stood,
The Jabberwock, with eyes of flame,
Came whiffling through the tulgey wood,
And burbled as it came!
One, two! One, two! And through and through
The vorpal blade went snicker-snack!
He left it dead, and with its head
He went galumphing back.
“And hast thou slain the Jabberwock?
Come to my arms, my beamish boy!
O frabjous day! Callooh! Callay!”
He chortled in his joy.
’Twas brillig, and the slithy toves
Did gyre and gimble in the wabe;
All mimsy were the borogoves,
And the mome raths outgrabe.