How to make an image clickable in jira comment, so it pops up as if you click on attached image in attachment area?

You want this to allow a small image in the comment to be expanded into a larger light box view:

!my-screenshot-image.jpg|thumbnail!

Per the source for JIRA 6.3, the following are also valid attributes for images:

align
border
bordercolor
alt
title
longdesc
height
width
src
lang
dir
hspace
vspace
ismap
usemap
id
class