It’s oval, resembles a pear.
Draw a wide elastic band of the underpants.
Separate the underwear with the help of the arc.
Captain Underpants has got the short legs.
Draw the stitches.
Separate the clothing from the neck using the semicircular lines.
Draw the cape.
They are short and thin.
Draw the palms.
Draw a wide mouth and the teeth.
Draw the eyes using the dots. His nos is a line folded on the edges.
Add some details.