I heard this expression from an Austrian commentator on a skiing video and couldn’t find anything on Google. It was used very excitedly!
It can be heard at 1:13 min in this video.
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The translation into standard German is:
Fahren wir heim!
The oa diphthong is rather common for the Bavarian dialects (the dialects spoken in Austria (except Vorarlberg) and South Tyrol are Bavarian dialects) and often replace ei diphthongs in standard German. Note the similarity to oans, zwoa, drei, gsuffa.
The oa in Foama, however, is a different way of pronouncing a long a. Bavarian distinguishes between different a sounds (compare English cat and bath) and a long bath-type a can often be diphthongised to something like oa — especially more to the eastern part of the dialect space, where the Austrian cultural centre is. Western Bavarian would tend to pronounce the r stronger, as in farma.