When I worked in the Kapahulu area, Rainbow Drive-In was conveniently located one block away from my office. Being a creature of habit (and slightly lazy and/or short on time), I frequently picked up a quick lunch at Rainbow Drive-In.
Parking is very tight and extremely scarce, which, fortunately, was not a problem for me since I came on foot.
My favorite lunch-on-the-go was Rainbow's cheeseburger deluxe, french fries, and a slush float. The float was the highlight of the meal, followed by the crispy, skinny fries, often served fresh from the deep fryer. The burger was your typical, home-style burger, not too big, but pretty decent for what you paid.