Women just have way more on their minds than men do. It's not that they're stupid, they just have at least 100x more thoughts going on than we do at any given moment. So they come off as air-headed or ditzy to us simple menfolk when we see them at a cash register completely clueless that they're going to have to pay for their purchase until the VERY moment when the clerk says, "Ma'am... Um, Ma'am?". But men are honestly only able to plan ahead so efficiently because we're not capable of the complicated thought patterns that women are.
I mean, I can't even imagine having to process and analyze every single conversation I took part in for the day, plus judge all of my coworkers outfits, and then calculate the exact amount of weight that Becky has put on since October, plus contemplate the fact that Jessica actually wore those shoes today (what a slut), and then try to figure out who is going to win The Bachelor this season, as well as internally debate whether I should dye my hair brown or red - but wait, when is my mani scheduled for again, maybe I should match my hair to my nails - oh, but I just got that new dress and I'd look sooooo good with brown hair in that dress, ugh, but I'm going to need to get tights, do they have tights at grocery stores? I don't know, I could've picked some up, maybe I should go look real quick while he's ringing these up, ...and so and so forth. ALL IN 10 SECONDS!
I'm telling you, it's a whole other level of brain activity. Men can't even comprehend it. Layers upon layers upon layers flashing by in an instant. We're absolutely incapable of even understanding their brilliance. And the end result is that we come off as being the smarter of the species because in our simplicity we excel at having a credit card ready before someone asks for it, or getting the friggin' keys out before we walk up to a door. But make no mistake, during those 10 seconds that you have to wait for her to fumble through her purse, her brain just ran laps around yours. Simpleton.