Aliens Love Dinopants by Claire Freedman and Ben Cort. Published by Scholastic.
My students LOVE all the underpants books and we have such fun with them.
Mallets 1 are the glockenspiels, Mallets 2 are the alto xylophones, and Mallets 3 are the bass xylophones. Substitutions always work great. I usually add some sound effects - something like vibraslaps or flexatone for when we sing "aliens" and something like finger cymbals for when we sing "underpants". Anything you add makes it fun for the students. I usually teach the song first, then the instrument parts on body percussion, then we put it all together.