Triple negative
From Teflpedia
A triple negative is a clause that has three elements of negation.
These may be found in some non-standard dialects of English, for example:
"I didn't say nothing to nobody".
This sentence would usually be interpreted as having negative concord. For example, it could have been spoken by criminal A denying to criminal B that he had spoken about crimes committed by criminal B.
According to the standard English logical interpretation of double negatives being positive (since two negatives make a positive), a triple negative would also seem to be negative (since three negatives make a negative).
In standard dialects, these may be occasionally found, usually as at attempt at obfuscation.