I've never had it so can't comment on taste. This article is the best I could find. Hope it helps. 

What is Egg Coffee?

Never did know of this. Place. Strange.

Love egg coffee - a must have when camping.  Actually, I think my mom got the recipe from her mother (as the Lutheran Church ladies used to make it in large quantities in the basement fellowship hall kitchen).  

Best cooked on a Coleman Stove or campfire. I've never measured anything so these are estimates:  fill a coffee kettle with about 8 cups water (just below the pour spout on a 12 cup pot) and bring to a boil.  Mix about 3/4 - 1 c. coffed & 1 egg well in small bowl.  Add about 1/4 c water after mixed so pourable.  Add to boiling water & boil until the foam subsides (about 5 min).  (Stay close & stir with wood spoon to avoid overflowing).  After foam is gone remove from heat & pour 1/2 c or so cold water into the pot.  This sinks the coffee grounds (that stick together because of the egg) to the bottom of the pot.  Enjoy!

My late mother-in-law (Swedish heritage) used to make it all the time. It was strong, but delicious. She used one of those old-fashioned percolators to cook coffee directly on the stove. She'd take out the piece inside the pot where you put coffee grounds in and just pour in the coffee grounds and an egg right into the pot along with the water to boil until done (taste and color were the rubric she'd use). But she didn't need to test it, she'd know when it was done. Then she strained it before pouring a cup. We were wondering though if only the egg white was used? Not sure. A great tradition... and it did have something special about it. All the Lutheran "church ladies" knew how to make it :-)

My Grandma (Joyce Carlson) ran Lundahl's Coffee Shop and lived above the coffee shop in the late 1970s early 80s. Whenever I'd stay with her for the night my uncle and I would sneak down and smuggle Hershey candy bars and throw those said eggs, presumably some for the coffee, against the basement wall. That is the only memories I can conjure up and sorry I did not try the egg coffee but I may have affected the egg supply at Lundahl's. I miss my Grandma Joyce!

I guess I should mention I was probably 5 and my uncle 8 at the time. :)