A phrase used when one is encouraging a peer to put maximum effort into a particular activity. Giving it the beans implies that the participant should without doubt ‘nail’ the task ahead. The ultimate battle cry. for example: Should i down this pint of fine beer? “...’Give it the fucking beans’ mate...” Should i smash this pricks windscreen? “...’Give it the fucking beans’ mate...” A fat man running to catch the bus, “...AY MATE, ‘Give it the fucking beans’...”

I've never heard of this expression before now, so you can safely assume that only a small group of people use it. That's one of the problems with urbandictionary: you can invent a phrase, get a few friends to vote for it and voila! you have "authentic slang". Anyway: there is a common expression, "to be full of beans". This means to be full of energy (specifically, Mexican jumping beans). Perhaps your phrase is a variation.