I'm pretty sure the particples would be "big upped" and "big upping", but I doubt that any of these forms will be widely attested.
Following on, here is the trusty google hit list:
- big up 97K (noun and verb)
- big ups 35K
- bigged up 670
- big upped 121
- bigging up 2140
- big upping 185
Without going into great detail, these hits seemed mostly legitimate uses and not typos or accidental combinations (they sent someone big up the ladder or whatever).
My theory was that the noun sense came first, but maybe not (cf. powerup in vidgame jargon, clearly from the verb). As I expected, the participles are much rarer than the uninflected form, but where the do occur they tend to support the verb form as primary.
-dmh 17:06, 26 Mar 2004 (UTC) (both entries)
I think the new analysis more nearly fits both theory and observation, but we really need more and better data. It all depends on how speakers analyze the term. If the first verbal sense is seen as derived from the noun, then big up will act as a unit, and the inflection will be on up. This is rare, but I find "on inned" as a past of "on in" from the sport/activity of hashing (itself in need of Wiktionary documentation).
On the other hand, if the speaker analyzes "big up" as purely verbal, then the inflection will be on big, as usual.
On writing this, I realize that the sense of "give significant respect or acclaim to" and the sense of "exaggerate the importance of" are probably just the same sense used in different contexts, with the noun sense derived from it. Nonetheless, one can also find big upped, so this is not the only analysis, even though it now looks like the primary.
I'm going to have one more go . . . -dmh 19:38, 1 Sep 2004 (UTC)