OK, transform your pig!
Cast on 32 sts. Knit 4 rows for the collar.
Main part of cape - row 1 knit
row 2 - purl
Row 3 - (first armhole row) knit 3, cast off 3 sts, knit to last 6 sts. Cast off 3 sts then knit last 3 sts.
Row 4 (second armhole row) Purl 3 sts, wool round needle 3 times and purl next st. Purl to last 3 sts. Wrap wool around needle 3 times before purling next st.
From now on, increase 1 st each end of every 4th row until cape is required length, approx 12 cm.
Finish with two knit rows.

Now, with the dpn, pick up 12 sts around the armholes and knit 3 rows before casting off to make two short sleeves. These help keep the cape on Super Pig.
Sew all the ends in.
I embroidered SP on the back in chain stitch for Super Pig, but anything goes.
Now put the cape on your guinea pig - careful with his little paws!
And off goes Super Pig on his first mission ...