I know it's from the very early 90's but I don't recall what it was for.
It involves a small child, a boy if I remember correctly, flushing random stuff down the toilet; things like toys and stuff.
I'm led to believe it was a plumbing repair ad, because (if I remember correctly), a man (his father, maybe?) was practicing golf inside the house or something--just go with it--when a pipe in the ceiling busts, resulting in an avalanche of colorful, little plastic blocks mixed with water. What occurs next, I don't exactly know (more than likely an explanation of the services if it is a repair ad), but it ends with the kid running back in to flush one last thing (which I can't quite recall). The ad ends as the logo for the product/service--whatever it was--fades up. I seem to remember a little snippet of a cavalry call used with the logo.