It happened while everyone just focused on Yellen's feedback regarding interest rates and all other FED issues. This was an important speech, as everyone was curious to see U.S. dollar's position against all other currencies.
All of a sudden, somebody held up a "Buy Bitcoin" sign behind Yellen.
This was certainly an interesting (and possibly historic) moment for bitcoin.
It has received a lot of coverage in the major news media, including CNBC and Marketwatch:
The guy who held up the sign behind Yellen showed up shortly after the testimony with the sign itself, his bitcoin donation address and the date as a proof.
It's the image of the day for sure! Good job!