Uh I know how to tuck. I do it every time I dress up.
What baffled me is how a thong is able to hold everything in place. I use an extra small Victoria's Secret hiphugger panty with a small Victoria's Secret hiphugger on top to tuck to go with spanx(that I use to hold in my hip pads) and the hiphugger panties are barely enough to contain me. I have Victoria's Secret Cheekini panties(a slightly more revealing bikini) that I spill out of when tucking, so I no longer wear them.
I can not think of anything more impractical for tucking than a thong.