Beat 1.Nf3 with 1...e5!!
No joke, that was a real game. Lasker once played this too.
https://www.chessgames.com/perl/chessgame?gid=1380383
It was a complete joke. Where do these trolls come from??
Also I don't know why NN resigned. Even if it was mate in 6 as one comment suggests, it's by no means clear. Why not give Lasker the pleasure of finishing it if he can? He could easily make a mistake in a simul, especially since it could end up with opposite coloured bishops here and white has an extra pawn and with no doubled pawns.
Some NNs seem to think they're cool in resigning early, the odds are stacked against the person giving the simul and the NN should play on.