LORELAI: Oh, they want a picture. How about the one of us sticking our heads through the carved out holes of Johnny Bravo and SpongeBob Squarepants?
Johnny Bravo, animated romantic comedy TV series created by Van Partible for Hanna Barbera which aired on the Cartoon Network from 1997 to 2004. The series focuses on Johnny Bravo (voiced by Jeff Bennett), a dim-witted Elvis-esque womaniser who lives with his mother. Episodes revolve around Johnny asking women on dates, although his advances are usually comically rejected, sometimes violently. The comedy derives mostly from celebrity guest star appearances and pop culture references, as well as adult humour – you can see why Rory and Lorelai would be fans of the show! Johnny Bravo helped launch the career of Seth MacFarlane, creator of Family Guy – you can see why writer Daniel Palladino mentions it, as he worked with MacFarlane.
SpongeBob SquarePants, animated surreal comedy TV series created by marine science educator Stephen Hillenburg for Nickelodeon, based on an unpublished educational comic book Hillenburg created in 1989 to teach his students about undersea life. The show revolves around a cheerful yellow sea sponge called SpongeBob SquarePants who lives in the fictional city of Bikini Bottom, beneath the real-life Bikini Atoll in the Pacific Ocean. Here he works as a cook at a fast food restaurant called the Krusty Krab, and interacts with other undersea characters. The show first began in 1999 and is still running, having won numerous awards and inspired an acclaimed Broadway musical, which opened in 2017.
Rory and Lorelai presumably had this photo taken during one of Stars Hollows many festivals. Note that Lorelai immediately suggests sending Harvard a photo of both she and Rory together, as if they are one person, or as if Lorelai will be attending Harvard by proxy.