Don't get me wrong, I absolutely LOVE tacos.
But yeah, I would be confused and consider it a miscommunication.
On a football message board full of football savvy fans, if someone makes a reference to a "hail Mary" play then I'm going to assume it's a low percentage long pass play, with the intention of scoring a touchdown, and I'll also likely infer that it was at the end of a half, when such plays are most common.