Howdy! can be replied to with just a nod and a smile. It simply means Hi! in Texan - not How are you doing?. Or you might reply, Hey Y'all Doon? if you want to engage in proper Texan interactions. Replying in proper English, well pronounced, with each syllable clearly spoken, is HIGHLY discouraged.
The crest of a wave is the point of maximum positive displacement, or upward movement, away from equilibrium, or an undisturbed state. The opposite of crest is trough, which is the point of the greatest negative, downward displacement.
2. the highest point or level: riding the crest of popularity. 3. a ridge or ridgelike formation. 4. the foamy top of a wave. 5. the point of highest flood, as of a river. 6. a tuft or other natural growth on the top of the head of an animal, as the comb of a rooster. 7. the ridge of the neck of a horse, dog, etc. 8. the mane growing from this ridge. 9. an ornament or emblem on a knight's helmet. 10. a. a heraldic device above the escutcheon on a coat of arms.