Open your crescent roll cans and break the dough into four equal pieces. This is easy to do because each can has an automatic break in the middle of the dough -- so just let it separate automatically down that middle section when removing it from the can.
Roll each dough section out into a rope on a large cutting board, making them even lengths and slightly narrower at the ends.
Pinch one set of ends together and fan the dough out slightly to make kind of a pitchfork shape.
I'm braiding mine in four sections here because it's prettier -- and it's not as hard to do as you might think! Just remember always to start from the same side: I go from the right, because I'm right handed.
Turn your cutting board so that the dough is vertical and the joined end is away from you.
Take the right hand section and braid it over the section next to it, then under the third section, then over the section on the far left.
Now, do it again. Starting from the far right, bring that section over, then under, then over -- and now your right hand section is over on the left.
Keep braiding your (faux) challah -- always from the right, and always over, under, over, until you reach the end.
Pinch the ends of the dough together and tuck them under the loaf to make it look pretty.
Beat your egg in a separate bowl and brush the entire loaf with egg, then sprinkle on sesame or poppy seeds if desired.
Bake on a greased cookie sheet for 20 minutes at 350 degrees, or until both the top and bottom of your challah are nicely browned.