Senza contesto specifico, più che proporre si possono fare scommesse, magari tenendo presenti le altre frasi…
Fermo restando che anche la proposta di Elena Zanetti "ci sta tutta", e tenendo conto che l'esclamazione "woah" esprime in genere stupore, sorpresa e meraviglia, io proverei a scommettere un soldino sul 3 (ma forse anche il 2 è plausibile):

go down

vb (intr, mainly adverb)
1. (also preposition) to move or lead to or as if to a lower place or level; sink, decline, decrease, etc: the ship went down this morning; prices are going down; the path goes down to the sea.
2. to be defeated; lose
3. to be remembered or recorded (esp in the phrase go down in history)
4. to be received: his speech went down well.
5. (of food) to be swallowed
6. (Bridge) bridge to fail to make the number of tricks previously contracted for
7. (Education) Brit to leave a college or university at the end of a term or the academic year
8. (usually foll by with) to fall ill; be infected
9. (Astronomy) (of a celestial body) to sink or set: the sun went down before we arrived.
10. Brit to go to prison, esp for a specified period: he went down for six months.
11. US to happen
12. go down on to perform cunnilingus or fellatio on
(Collins English Dictionary – Complete and Unabridged © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003)


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Note added at 9 hrs (2015-10-15 07:09:46 GMT)
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Tenendo conto che l'esclamazione "woah" può essere usata anche nel senso di "slow down" (o "stop", p.e. come ordine per il cavallo), provo a scommettere un altro soldino su:

"qualcosa sta per smettere di funzionare"

In base a:
go down - stop operating; "My computer crashed last night"; "The system goes down at least once a week" crash
(Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.)