lit. Eggs (huevos)
Implication that one should go fuck one's self or one's mother.
In an urban setting, the use of this rich expression is highly offensive and should only be deployed spontaneously as a genuinely and heartfelt response to a direct urban offense, such as: un-granted honking, aggresive lane-cutting, vulgar remarks of sexual nature to one's female companion, etc.
Could be used semiotically, phonetically or combined.
Notice the palm facing to the front as fingers crouch with pinky bent all the way back. Native users of güevos display a hardwired reflex that prompts one's hand to adopt the position and describe a violent forward motion (starting around the solar plexus area (where every genuinely heartfelt emotion stems from) and going outwards). Arguably, crouching fingers are a refinement of an original hand posture where the middle finger is tense upward sided by two bent fingers (eggs) portraying a man's aroused genitalia.
A proper use of güevos usually involves an epithet describing the character of the recipient. Usual endings are "puto", "cabrón", "pendejo" or in combos: "pinche puto", "pinche pendejo" and so on.
(Following video is only illustrative since a genuine portrait can only happen impromptu)