The commonest answer I get after telling someone 'Thank you' is 'Mention not.'
If I answer something like this, many would turn this sentence down
That place is so exciting, I want to go ~ Go not. There could be a snake.
But then if I answer this in a traditional way, there's no problem!
Thank you. ~ Mention not. You can ask for such favor any time.
Note: 'Go not' is just one example. I mean all such verb to be used with not. For instance, talk not, walk not, like not, study not, sleep not instead of don't talk, don't like, don't study… and so on.
Best Answer
Go not is archaic. It's ungrammatical in Modern English, but people are familiar with this construction as an archaism and will understand anyway. To put it another way, it's grammatical, but the grammar it's part of is that of an older form of English.
Here's a simplified timeline:
Afterwards, the narrow distribution of the reduced form n't allowed it to be reanalyzed as an inflectional affix, which is particularly noticeable in inverted sentences. The affix -n't inverts along with the auxiliary, but the independent word not does not, so Doesn't he walk corresponds to the uncontracted form Does he not walk, not to *Does not he walk—although to this day Heavy NP Shifts result in a similar structure from time to time.
*Mention not is ungrammatical for another reason as well. Mention is transitive, so in the older grammar it should instead be Mention it not, corresponding to the modern Don't mention it.
Of course, if Mention not is really that common in Indian English, then there's nothing wrong with using it. But when I searched, I was unable to find any examples in Corpus of Global Web-Based English (GloWbE); I found only one result listed under Indian English, and that example was a false positive.