Incredible!
Explanation
The Joke
A man is excitedly examining what appears to be a piece of amber with a mosquito trapped inside, crystallized during the late Miocene epoch. He launches into a breathless monologue about extracting blood from the mosquito to find the DNA of ancient megafauna, and how he could bring back the Teleoceras, the sabertooth tiger, or even the mastodon. His partner keeps trying to interject with increasingly urgent "Okay" and "Stop it" responses. The final panel, labeled "Earlier," reveals the punchline: the woman had simply asked, "Do you have a condom?" and the man replied, "Uh, yeah, in my wallet. It might be a little old."
The Humor
The joke is a parody of the premise of Jurassic Park, where scientists extract dinosaur DNA from mosquitoes preserved in amber. Here, the "amber" is actually just a very old condom wrapper in the man's wallet that has become so aged and crystallized that it resembles a geological artifact. The humor lies in the absurd escalation: a man turns a deeply embarrassing admission (carrying a condom so long it has practically fossilized) into a grandiose scientific fantasy. It also comments on how some people deflect from awkward situations by going on tangents. The woman's growing exasperation contrasts perfectly with his oblivious enthusiasm.
References
The comic directly parodies the 1993 film Jurassic Park (based on Michael Crichton's 1990 novel), in which scientists clone dinosaurs from DNA extracted from blood found in mosquitoes preserved in amber. The Teleoceras was a genus of rhinoceros from the Miocene epoch, and the sabertooth tiger (Smilodon) and mastodon were Pleistocene megafauna -- though the Miocene dating in the comic is played for comedic exaggeration of just how old the condom is.