A suitable substitution for a hand shake if risk of spreading illness is present. Perfectly acceptable among well known politicians.
An unusually awkward fist bump between local politicians and foreigners who do not understand idiotic American customs.
A way of avoiding sticky, nasty, or clammy palms in a hand-shake while also making the other person feel cool and hip.
The Dalai Lama visited Memphis, TN and greeted the Mayor with an unusual fist bump, birthing the 'dalaibump.'
The reason for fist bumping as opposed to hand shaking was to reduce spread of possible Swine Flu and to also welcome the Dalai Lama. Or so they say.
Jennifer: That dude's hands are always really nasty.
Jessica: I don't think he washes them. Ever.
Jennifer: He always wants to shake my hand. And then I always have to wash my hands after. Sick...
Jessica: Dude, you should totally dalaibump him instead.
The ever health-conscious Jim and Christopher dalaibumped to avoid the spread of dangerous disease and plague.