Well yolk is yellow, so shaving cream is not good, and the 'whites' are clear until they are cooked.
How is it being blown out - in one burst all over everyone, or is it going to be huff, puff and ooze out. In any case, suspend belief for the moment. Maybe make some custard (or use UHT shop bought stuff) and place it in a reservoir, which has a simple sliding trigger mechanism (nothing too technical) then as he 'blows' (whilst pointing the egg down) he can pull the triggering mechanism, allowing gravity to work.
Or use a shaving cream can and have him pull the trigger on the can whilst blowing - make it look like he is actually holding the egg, but have the can hidden inside.
Theatre is about suspension of belief. Just because he is blowing an egg, does not mean his breath has to do anything.
--Edit--
Another idea - use a relatively thick custard or creame and use a sauce bottle - you know the soft plastic squeeze bottles...