The author just noted that the flour dough rolled into a tubular shape "long and fat as a sea slug" is "como pene," which means "it's like a penis." Then poking the dough, Leandro says, "como bato." "Bato" is a Mexican slang word that is roughly equivalent to 'dude' in English.
One can imagine Leandro making fun of the long, slug-shaped flour dough as follows: "It's like a penis." Then laughing, he adds, "it's like a dude."