This is based around my standard hat pattern. The large size is loose on my head (but would probably fit an adult male head fine). The medium is my normal hat size -- it fits very snug. If you work it with a hook smaller than 'normal', the large size fits my head smugly. I found that out by accident.
Materials: Worsted yarn in red, orange, and yellow. Crochet hook, size I. Cardboard scraps. A yarn needle.
With yellow, chain 4.
Round 1: Do five dc in the fourth chain from the hook. Join with slip stitch to chain 3. (6)
Round 2: Chain 3 (counts as first stitch). Dc in same stitch and 2 dc in each stitch across. Join to chain 3 with slip stitch. (12)
Round 3: Chain 3. 2 dc in next stitch. Repeat dc, 2 dc in next stitch five times. Join to chain 3 with slip stitch. (18)
Round 4: Chain 3. Dc in next stitch, then 2 dc in next stitch. Repeat 2 dc, 2 dc in next stitch five times. Join to chain 3 with slip stitch. (24)
Round 5: Chain 3. Dc in next 2 stitches, then 2 dc in next stitch. Repeat 3 dc, 2 dc in next stitch five times. Join to chain 3 with slip stitch. (30)
Round 6: Chain 3. Dc in next 3 stitches, then 2 dc in next stitch. Repeat 4 dc, 2 dc in next stitch five times. Join to chain 3 with slip stitch. (36)
Round 7: Chain 3. Dc in next 4 stitches, then 2 dc in next stitch. Repeat 5 dc, 2 dc in next stitch five times. Join to chain 3 with slip stitch. (42)
Round 8: Chain 3. Dc in next 5 stitches, then 2 dc in next stitch. Repeat 6 dc, 2 dc in next stitch five times. Join to chain 3 with slip stitch. (48)
(For a large hat, add this round: Chain 3. Dc in next 6 stitches, then 2 dc in next stitch. Repeat 7 dc, 2 dc in next stitch five times. Join to chain 3 with slip stitch. (54))
Round 9: Chain 3. Dc around, join to chain 3 with a slip stitch. Change to orange.
Rounds 10-15: Chain 3. Dc around, join to chain 3 with a slip stitch. On last round, finish off.
Ear flap: Count 5 (7 for large) stitches from the back seam.
Row 1: Join red with front post sc, then do 12 more fpsc across. Ideally, you want to make it so that the tops of the stitches are on the inside of the hat.
Rows 2-7: Chain 3, turn. Dc across
Rows 8-12: Chain 3, turn, skip an additional stitch. Dc across to the last two stitches, then decrease. This should decrease by two each row.
Row 13: Chain 3, turn, slip stitch to last stitch in previous row, finish off, leaving a long tail.
Finishing: Weave in ends. Take a doubled over length of red yarn and join with a hitch knot to the chain 3 at the end of the ear flap. Trim to match the end.
To make the pom pom take a length (I used about 4 meters) of each color of yarn, and cut two donut-shapes out of cardboard (I'd say mine were about 4 inches/10 cm across, with a small hole in the center) and hold them together. Wrap yarn around the donut, then trim the yarn between the donuts. Thread a piece of yarn in between the donuts and tie it off. Fluff out the pom-pom and sew it to the crown of the hat.