BBC News - Caption Challenge: Downward dog 5 September 2013 Last updated at 12:36 Your witticisms for... ... a topical photo It's the Caption Challenge. You can submit captions for this week's picture using the "send us a letter" form on the right. You, ahem, no longer need to be registered to take part. Entries are accepted until 12:30 BST on Friday. The winning six will be highlighted here at or about 13:00 BST on Friday. There is still no prize, except the traditional small quantity of kudos. This week, a dog sits amid amid an outdoor yoga session in Jacksonville, Florida, USA. PDF download Full rules can be seen here[16KB]