According to the data base at lichess, after 1. d4 Nf6 2. c4 e5 3. dxe5 Ng4 4. Bf4 Nc6 5. Nf3 Bb4+ 6. Nbd2 Qe7 7. a3 Ngxe5, 8. axb4?? has been played 27,409 times (including played by a player with a rating 2300+), and it is in fact the second most popular move in this position. Black wins 99% of the game after 8. axb4.
[fen "r1b1k2r/ppppqppp/2n5/4n3/1bP2B2/P4N2/1P1NPPPP/R2QKB1R w KQkq - 0 8"]
Another example: after 1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4 Nd7 5. Qe2, 5... Ngf6?? has been played 16,366 times (including played by a player with a rating 2600+) and white wins 98% of the games after 5... Ngf6??.
[fen "r1bqkbnr/pp1npppp/2p5/8/3PN3/8/PPP1QPPP/R1B1KBNR b KQkq - 2 5"]
Statistically speaking, what are the most popular opening blunders?