There's nothing more fundamental in learning a new language than the greeting. "Cómo estás" and "Muy bien" can be found in the first few pages of just about any Spanish textbook. But what about when you've outgrown "todo bien"? There are a limitless number of common responses you might give such as "todo tranqui(lo)" or "todo en orden". Here's another you might not have heard before: Al pelo (literally "bareback").
Like most phrases the seem to make little sense at first glance, "al pelo" has an interesting back story. During the time of the Spanish colonial rebellion, especially in the area of Columbia and Venezuela, the resistance forces were severely under equipped. They would often steal or raise horses to be used in battle, but they lacked the resources for saddles.
Only the generals had mounts and the common cavalry were often bareback. After a time, the phase "al pelo" came to mean heroism in the face of limited means. When askes how a journey was, one might reply "al pelo" to means they face obstacles but came out unscathed. Eventually the phrase became synonymous with strength, health and valor. Today "al pelo" means fantastic when referring to oneself.
So the next time someone asks you how you are in Spanish and you're feelign on top of the world, you might tell them, "Al pelo"!