\'Bob\'s your uncle\' means \'there you go\'.
As in:
\'Could you please give me directions to the nearest purveyor of fine scale models?\'
\'Certainly, continue down this road, turn left and Bob\'s yer uncle\'
Or:
\'Excuse me, I appear to have accidentally inserted a scalpel into my eye, could you please direct me to the nearest hospital?\'
\'Certainly, continue down this road, turn left and Bob\'s yer uncle\'
Who exactly \'Bob\' is is something of a mystery to me. Likewise why he is ones uncle is also unkown to me. If wishing to be a little \'wacky\' in a kind of side parting, trousers too short, novelty tie kind of way, one could substitute \'uncle\' for \'aunty\' to create an amusing gender confusion.
As in:
\'Excuse me, I appear to have sat on my extensive collection of English Civil War pikemen and they have become irremovably attached to my now stinging buttocks, could you please direct me to the nearest hospital or acupuncturist?\'
\'Certainly, continue down this road, turn left and Bob\'s yer aunty\'