Spending a half hour picking out paint, and then when the H.Depot guy telss your son " your gonna have a pretty blue room now 'eh", you say "no, it's for a fish tank", the guy looks at you like your crazy and your kid suddenly gets dissapointed.
Going back to Lowes with a great big bag of plumbing fittings and returning them with a big stack of receipts for 30.00 worth of store credit, then going right back to the plumbing section to buy "the ones you now need"