If you can’t see it, the gist of it is that two men are sitting at a bar drinking beers and watching TV, while the bartender has his back turned and is reading a newspaper. The caption says, “the Lehman Brothers on the town.”
I think the joke is that they’re at a little neighborhood bar, not one of your fancy/trendy/expensive caviar and vodka joints or what have you. Their “on the town” now is just a cheap domestic beer in a dive.
I would interpret it as reflecting the change in the meaning of the words “Lehman brothers.” At one point not so long ago, a reference to “Lehman Brothers” would mean the venerable investment banking firm. Now, “Lehman brothers” just refers to two brothers who happen to have the last name Lehman, since the other Lehman Brothers has ceased to exist. It’s a joke about the devaluation of the words.