Her date-to-be is an exchange student from China pictured below in an inflatable suit. He and his friends won a dance contest in suits like this so they teamed up again for this invitation.
The other thing you need to know is that Lindsey and I went to New York in December with Jay (he was working) and she and I were lucky enough to go see the Broadway show Alexander Hamilton (featuring Lin-Manuel Miranda, the show's genius creator as Alexander Hamilton himself). Since then, we have really enjoyed (OK, obsessed about) the music, book, anything Alexander Hamilton, hence the reference in the sign.
Apparently, this boy (his name is Nick) recruited the help of two of Lindsey's closest friends. One of them brought her in and filmed the whole thing and the other was playing the guitar and singing. Nick and two friends in matching suits did a reprise of their winning dance which ended with the unveiling of the prom invitation. Naturally, the teacher of the classroom he used was also in on it.
Those of you who know Lindsey personally understand exactly how much she appreciated the creativity involved with all of this. She is into performing arts and would "get" this quicker than many.
I think (and yes, of course I am biased) that Lindsey is pretty special. As such, I am so happy that Nick went to such trouble to fine a unique way to invite her to prom.
Now, to find a dress... (!)