I agree to the previous answer: Saying something like "zum Hier-Trinken" is probably the most common and most precise answer.
One additional remark, because I am a little bit of a "grammar nazi" (and proud of it ;-) -- Such constructions are rather colloquial speech, one should not use them it elaborate written text. The problem is that the construction "zum Trinken" is grammatically something like a gerund, and in German language (unlike Latin, where it originally came from) such gerund constructions better do not have too many adverbs (or even objects, etc.) by themselves. It just feels awkward if one tries to turn such a gerund form into a full independent sentence, and even the single additonal word "hier" disturbs a little bit.
So, as a result, the "zum Hier-Trinken" is o.k., because it has become common speech, but be careful with generalising this to similar constructions.
Because of this, I, personally, often use an answer like "[Nein,] ich bleibe hier.", which is not comparably precise, but avoids this awkward feeling ;-)