This is a non-exhaustive list of concepts that have been used so many times by so many different people that nobody should ever use them again, unless they think of a spin on it that's so clever that it makes up for how bad the basic concept is, which you won't. I'm not going to bother with references to specific battles where they were used. Just read and learn.
The list will be updated as suggestions come in.
Defeat / Da Feet - This one is so pathetically bad and overused that it's more often used ironically than seriously at this point.
Bars / Prison - Prison cells have bars on them. We know this. While I'm at it, I should mention bars / phone charge and bars / establishments that serve alcohol in the same category. They're not QUITE as overused but pretty close. And, for the love of God, do not ever say anything about "the bar exam."
Lines / lines of coke - See above.
Bar buryin' / Barbarian - A good example of a wordplay that's not really trivial, but obvious enough that a bunch of different people have thought of it.
Sho / Show versus me and Lock(hart) / Lock (as in a door) vs Lockhart - Must be the 2 most used/abused/overused nameplays ever.
Fair In Height / Fahrenheit vs Celsius - The Sho / Show and Lock / Lock ones are super obvious, but it escapes me how so many people have apparently thought of this exact same wordplay by themselves. I bet they all thought they were geniuses when they came up with it, too. Don't let yourself be the next one.
Calling a round object a ROUND - Not just overused (to a ridiculous extent at that) but nonsensical. Even worse than defeat / da feet in that regard.
NOTE: This doesn't apply to food items or coins made of precious metal due to little-known grammatical technicalities.
Anything about "da hood" which ties into KKK outfits, the hood of a car, or hooded parkas/jackets/sweaters/etc. - Anyone who does this deserves to be sent to Guantanamo Bay and subjected to hooding (look it up if you don't know what that is).
Sole or Soul nameplays against Seul - Don't. Just don't. You're not clever or original. This is in about the same category as Sho(dan)/Show or Lock(hart)/Lock. Shout outs to @
KG The Prince for reminding me of this.
Disguise / Da Skies - Not much I can say about this one, other than it's played and terrible. Big ups to @
Denton for mentioning this one.