Fight fire with fire
Nope! I'm going to fight fire with fire retardant chemicals! It's the reason we keep a fire extinguisher in our kitchen and not a fire retinguisher.
Sunlight is the best disinfectant
Nope again, Kal Penn! Sunlight might kill vampires, skin cells, and my will to live, but most bacteria and viruses are perfectly okay with the occasional-to-frequent tanning sesh. What you want is a solid filter, a decent dose of chlorine and/or ozone, and a good and hearty hour or so of UV irradiation.
Don't feed Gremlins after midnight
Yes, we've all seen, and based our wedding vows on, Carl Sagan's semi-autobiographical cinematic classic Gremlins. But that movie got more wrong than it did right. Feeding Gremlins after midnight is as fine and randy as John and Candy.
Fit as a fiddle
have you ever tried jamming your fiddle into an undersized overhead compartment? Spoiler alert! It doesn't fit.
Laughter is the best medicine
Laughter is the best aphrodisiac.
Every rainbow has the crushing realization that a rainbow is ephemeral at best, fleeting at second best, and will literally suck your soul out of your soul-hole directly through your eyes
That one is more of a family motto than a cliché.