Irracional translates to "irrational". It's a strong adjective that describes someone acting without reason or logic, often driven by intense emotions.
In the song, the singer uses this word to describe his own behavior after seeing his ex-lover with someone new. He sings, "Na sua ausência eu me tornei um cara irracional" (In your absence, I became an irrational guy), highlighting how heartbreak has led him to act impulsively and destructively, like breaking "copos e garrafas" (cups and bottles).
Have you ever run into an ex at the worst possible moment? In "Copos E Garrafas" (Cups and Bottles), Lucas Lucco sings about this exact nightmare scenario. He unexpectedly sees his former love with a new partner, and to make matters worse, she's wearing the perfume he gave her. The singer is overwhelmed with jealousy, which boils over when the new couple kisses right in front of him.
This intense emotion leads to an explosive reaction. He admits that "rage and jealousy dominated my mind" and he starts "breaking everything I saw in front of me." However, he makes it clear that the shattered glass on the floor is nothing compared to the "damage in my heart." He knows his actions are irrational and embarrassing, but he can't control them. The song is a powerful confession of heartbreak and a desperate plea for his ex to stay away, warning her that if he sees her with someone else again, the outcome will never be different.