Guapo (Spanish for “beautiful,” at least in Spanish outside of Argentina) comes from the Latin vappa which meant, “flavorless wine.” (The Romans must have drunk a lot in order to have a word that just means, wine that has no flavor!).
From that same Latin root vappa, we get the modern English word… vapid. A vapid thought is, after all, flavorless.
Although only the ‑p- root remains in both words, we can see how the ‑v- sound transformed into the ‑g- sound (both are similar), while it remained intact in the English vapid.