Affoga means "drowns" or "suffocates". It's a strong and evocative verb that immediately brings a sense of intensity and danger.
In the song, Mecna uses it metaphorically in the line "In questo cocktail ci si affoga" (In this cocktail, one drowns). This suggests that the problems and reality are so overwhelming that they can consume a person, much like drowning in a drink. It's a powerful image that makes the word stand out.
Mecna sings about a relationship running on distance and bad timing. The title line, "Ed ho guardato un'altra stasera" (and I looked at another girl tonight), is a confession, and he follows it straight away with a needy question: "Ma ti sono mancato almeno un po'?" (but did you miss me at least a little?). He wants credit for being honest and reassurance at the same time.
The passport image is the sad, specific detail: "Sul mio passaporto ho due pagine senza un viaggio insieme" (on my passport I have two pages without a trip together). She is "a Parigi per la moda" (in Paris for fashion) while he is "giù in Puglia con i miei" (down in Puglia, the heel of Italy, with my family; i miei is everyday Italian for "my folks"). Her reply to his confession is the threat repeated in the outro, "Ti sparo o ti ammazzerò" (I'll shoot you or I'll kill you). It is jealous exaggeration, not a real threat, and the song treats it almost fondly. Useful phrases here: pelle d'oca (goosebumps) and volersi bene (to care for each other), which is how Italians talk about love without saying amore.