Navy Blue is a fanmade Sing-a-ma-jig. He is navy blue, has red hair, the same ears as the pumpkin, black circle eyes, a purple nose, a dark green mouth, the same arm pose as the Ghost, the same feet as the Birthday Tenor Sing-a-ma-jig, the same shirt as the pumpkin but the stripes are yellow and red instead of black and purple, the same voice as the Light Blue one and he sings "Baa Baa Black Sheep, Do you have any wool?". He signs on by saying "Salutations", enters song mode by saying "Song" and signs off by saying "So Long".
Navy blue sing a ma jig

This is what he looks like.