The third chakra, located at the solar plexis, is said to be lemon. Note that "solar plexis" is associated with the power of the sun (solar-sun). Laser Lemon, then, is associated with positive thinking, with sunshine. The solar plexis is where we gather our courage and will power. When this chakra is not functioning properly, we are fearful or "lemon bellied."
Laser Lemon appears to carry both positive (sunshine, happiness) and negative (cowardice, illness) connotations. This may be why we use yellow as a sign of caution between red (danger! stop!) and green (safe! go!). Laser Lemon seems to be a compromise, a middle way, between positive and negative. Indeed, the lemon chakra is right in the core, in the middle, of the body.