There do seem to be different interpretations - as you'd expect for a neologism:
A contributor to a mailing list for Japanese-English translation that I read reports that the verb obamu is gaining currency on the Kyoto University campus. He writes, “It means something along the lines of, ‘to ignore anything which appears to make you likely to fail or (be) wrong, and blindly surge ahead (preferably chanting, “yes we can, yes we can”)’.” He adds that he heard a friend jokingly try to cheer someone up by saying, “obandoke, omae.” (オバんどけ、お前.)
If I had to translate that on the fly, it would come out something like, “Lighten up and think positive, guy!”
I found it as an entry dated 22 September in a collection of slang and modern usage put together by the Japanese Teachers’ Network in Kitakyushu. Here’s what they write:So to those who find themselves newly added to the unemployment rolls, or to one-time allies in Eastern Europe facing alone a newly resurgent Russian Bear, let me just say "Hey, why are you so down in the dumps? Obandoke, omae!"
obamu: (v.) To ignore inexpedient and inconvenient facts or realities, think “Yes we can, Yes we can,” and proceed with optimism using those facts as an inspiration (literally, as fuel). It is used to elicit success in a personal endeavor. One explanation holds that it is the opposite of kobamu. (拒む, which means to refuse, reject, or oppose).
They give the following example:
Or, “Hey, why are you so down in the dumps? Cheer up, cheer up!”
Ampontan is a very interesting blog that gives you inside baseubaru from the Land of the Rising Sun.
Hat tip: Don Surbur.