St. Expeditus is a new one to me, too. The story the catecumen told me was that he was the saint of expeditious solutions, emergencies, desperate cases, and procrastination. He is depicted holding a cross that says today and stepping on a crow that represents tomorrow. IOW, convert today, not tomorrow.
Of course I googled the name. Since St. Expeditus died about the fourth century, legends abound. And there's no proof that such a person ever existed. It has been speculated in a few sources that the name comes from the shipping instructions put on a box of bones.
However, I'm always amazed that there's some truth in these legends. So take the stories as stories. The image of the saint is that he was a soldier. He wanted to convert to Christianity; that's why the cross. However, the devil appeared to him as a crow and tried to talk him into waiting. So Expeditus stepped on the crow. He wanted to convert immediately!
I even read where voodoo and hoodoo with their corrupt interpretation of saints and think of St. Expeditus as the patron of death and is used to curse others. May God deal with them!
Being Catholic, I don't worry wether or not there really was a St. Expeditus. Our prayers to saints go to God. He knows.