According to Screenrant, as well as a couple of other reviews I looked at, The Joker is indeed saying "worth a google". In the English language, the proper name Google has become slang for looking something up on the Internet - even when not using the popular search engine. The term is typically used as a verb (i.e. - "google it"), but can also be used as a noun (i.e. - "let's do a quick google and find out"). It is the latter which The Joker is using in this context.
For anyone who has seen a Batman film, read a Batman comic, played a
Batman game, or has a general knowledge about the character, some of
these villains will be recognizable. Riddler (Conan O’Brien),
Scarecrow (Jason Mantzoukas), Bane (Doug Benson), Two-Face (Billy Dee
Williams), Catwoman (Zoe Kravitz), and Penguin should be familiar, but
after that, it takes a really hardcore Batman fan to recognize the
Crazy Quilt, Eraser, Polka Dot Man, Mime, Tarantula, King Tut, Orca,
Killer Moth, March Harriet, Zodiac Master, Killer Ghost, Clock King,
Calendar Man, Kite Man, Catman, Zebra Man, and Condiment King, on the
other hand, will be new to most. Just like the pilot in the video,
most may wonder if these are all really villains Batman has faced over
the years. As Galifianakis' Joker says, "It’s worth a Google."