The next sentence: Tengo alergia al marisco.
Tengo – “I have” – comes up again and again, so it gets a fixed image: you are holding a berry and dancing the tango like an elephant (tengo). The allergy shows itself as a scratchy throat that makes you bray like a donkey: “hee-haw”, in German “I-a” (alergia).
And why the allergy? You bought an eel at the market; it was enormous and cost almost nothing (al marisco – from the German “Aal”, “Markt”, “riesig” and “kostet”: “eel”, “market”, “huge” and “costs”).