I'm off to Starbucks near London's Regent Street for a shot as a coffee barista. I sense trouble brewing, as I contemplate spending six hours surrounded by that aromatic black magic. Talk about indulging your vices: it's like sending John Terry away to a hotel full of his team-mates' wives and girlfriends.
I may be a certified caffeine user, but I'm hardly a Starbucks devotee. Too much hoopla. I preferred the old Nescafe days, when you could woo people by simply shaking a handful of beans. But things have moved on, and my day kicks off with a tasting session, courtesy of Alan Hartney, Starbucks' UK coffee ambassador, who shares his knowledge of everything from harvesting the crop to brewing a cafetiere (optimum time: four minutes).
It's genuinely enlightening. We sit around in the store's basement, hands cupped around espressos held to our noses as we inhale the fumes. 'What scent are you getting?' asks Alan. 'Grapefruit,' says Maria, the store manager. 'Coffee,' I say.
Alan enthuses that this blend, the Colombian Narino Supremo, goes well with potted shrimp. Jesus. He's only sniffed one and he's high already.
Time to taste. The technique is to inhale sharply, spraying the coffee along your tongue's sensors, from sweet back to salt, sour and bitter. Get it right and you'll have a taste sensation - and sound like the flush on an airplane toilet.
I'm flying in no time. I've only been here half an hour. 'Ambassador, with these fruity Kenyan notes you are really spoiling us,' I giggle to myself. By the time everyone else is detecting green pepper in the Asian-Pacific blend, my brain is vibrating and I'm halfway to manic.
Now that I'm suitably wired, Alan puts me 'on bar', tackling my first drink - a simple cappuccino. One shot of espresso for a tall (that's Starbuckian for 'small'), which should take 18 to 24 seconds to drip out of the machine. Steam the milk to 160 degrees and get the nozzle to the right depth to give it a smooth, aerated sweetness. It's harder than it looks.
At 11am things suddenly crank up. There's a queue building and I'm frothing. It's chaos. As I'm fixed on the steaming, a line of cups starts to stack up beside me, duly marked 2xNC, C, FW, CHC, VNL. I look down the line of tetchy-looking punters and feel like a pusher. PCP? LSD? I try to avoid contact with their impatient caffeine-drained eyes and zone in on failing to properly steam the milk.
Alan rescues me and sticks me in the middle of the chain - marking up the cups and adding syrup when required. I'm doing a skinny extra shot vanilla latte. I've got no idea what's going on. I'm not alone. More than one customer comes in struggling to decode their own order from a crumpled note.
Bafflement aside, the vibe here is actually relaxing, even if does all feel like a living excerpt from No Logo, Naomi Klein's anti-branding tome. Morale is high, and the 'partners' laugh with each other and their iPhone-touting customers. They're proud of their work. There's a lifetime of coffee knowledge to gain and share. It's a world away from flipping burgers.
Not that public perception would always reflect that. District manager Brian Aherne pops in for a chat and says as much: 'Starbucks has an awful image, despite being ethical.' He highlights community projects he runs, from working with the Samaritans to training an Eritrean girl who arrived here with nothing but dreams of running her own coffee chain. Not that they like to talk about it, he tells me (a journalist).
Back on bar, the buzz is all about the flat white - a stronger, smoother version of the latte that's been a word-of-mouth hit among customers.
My shift ends with another round of tasting. This time from Ethiopia - the birthplace of coffee, where one pioneering farmer apparently saw the stimulating effect that certain beans were having on his goats and started eating them himself. We may think that's weird; he'd probably think we're mental for drinking it with lemon drizzle cake. Now this even I can taste. And it's pretty damn good, I have to admit.