Mine just happened. I made bingos with TRAINED and TAINTED, back to back. In my next game, I made TRAINED again, and then TWEETING, back to back. I assume for the top players in the world, back to back bingos aren’t all that unusual. But I’ve only been playing for a month, so I’m pretty proud, but to be honest, even more amazed.
Oh, please do share. Or doesn’t anyone play anymore? 
My last game I had absurdly unlucky draws from the bag, leaving me with six vowels and one consonant for several turns in a row. No way was I going to get a seven-letter word, let alone two back-to-back.
Two games ago, my opponent left an opening for the triple word score on the top row of the board, and I played ‘minx’ across while connecting to ‘ho’ downward. The word ‘mho’ I remembered because it’s a cute play on the SI units in electricity, in which ‘ohm’ spelled backwards was once used as a unit of conductivity (conductivity being inversely proportional to resistivity, which is measured in ohms).
Mine was years ago around 1972. It was at the end of the game, when there were no tiles to draw and every point counted. We were playing in a mixed group with partners. I looked at the tiles. There were two lines parallel to each other, setting up two T’s with a space between them. I had an “I.”
I said, “I have a word, but it wouldn’t be polite to use it.”
My partner (female) looked, then cracked up.