"That's not true!" or "That isn't true!" Which one is correct?

Cuckoo, ''yep'' is most definitely a word. I use it a lot and am never told that I'm speaking bad English.

Cuckoo, What about ''nope''? Are you saying that that's not a word either?

Joe,

If I were you, I'd ignore that individual.

Cuckoo: another word you will see in the dictionary is dope....it has several meanings.......Cheers :-)

PS: come to think of it....a Cuckoo isn't necessarily a parasitical bird either..

Cuckoo, don't say "dic". Say "dictionary". learn English.

Dic means dic. as an abreviation of dictionary. You think a call it my dick. Bitches complaining to Cuckoo! It's socking. Don't make fun of me, gays!

I'll say ''yep'' if I want to, Cuckoo. ''Yup'' is slang but ''yep'' is very acceptable.