Those shirts were introduced on the 3/14 episode when they finished the zipline challenge. They said it’s their power word and means “circle of the universe”. They did pronounce it Ta-tow (rhymes with wow!).

The Amazing Race 3/14 Recap – TTOW, And Other Hard To Prounounce Words

The Hippies jump in their hippie mobile and start out the day with their typical fun. Find their way to the zipline, scare some of the other teams while they wait for the zipline to open, and jump on the hoods of some of the other cars—generally they clowned around more than Jon and Al from season 4. Their secret, made up word for everything exciting is “TTOW”, pronounced Teh-tOW for those of you that are hooked on phonics like I am. It’s so special to them that they feature it on their shirts as part of their matching Super Hippie outfits! They zip quickly, get themselves to Russia, and Tyler decides to take the plunge. TTOW! Their taxi driver gets them to the cathedral quickly, and upon finding the clue, both boys take a minute to admire the sheer beauty of the place that they are in. Ornate is an understatement. Dude, I wish we had a joint! TTOW! They head for the “Scrub” detour, but their taxi driver has no clue where the trolley park is. They end up in some residential neighborhood in Moscow, and eventually just abandon the cab to try and find the trolley’s on foot. Eventually they give up, and head back over to the “Scour” detour to open nesting dolls. Tyler pulls a rabbit out of a hat to find their clue (TTOW!!) and bound off to meet Phil in Red Square. They arrive…