Tag indicates that there are no yukkuri in the image, nor anything which looks like a yukkuri (such as a yukkuri face on something), nor are there any indications that yukkuri are involved.
It does not automatically apply to images that have no_yukkuri in them; for example, the tag is inappropriate for images that appear in a series which does involve yukkuri, even if there aren't any yukkuri in that specific picture.
The tag implies that there might not be any yukkuri involvement at all, and is often (incorrectly) used to indicate that the picture might be considered for deletion (hence the tag's rather sarcastic tone).
