1000 hours in ms paint
Usually used for the worst kind of pictures – art that is so incredibly poor-quality that looks like a crude ms_paint drawing. For example, copy-pasted assets, such as heads or other body parts, done in ms_paint quality; bad linework; lack of detail; or disproportionate body parts. Art with this tag is rarely approved on today's standards; nearly all examples that have been approved are either grandfathered content, a meme, an obviously comedic post, or — it must be stressed that this last case is astronomically rare — somehow clear that it's a stylistic choice rather than a mere lack of skill (which you'd better have an incredibly convincing argument for; saying something is a style does not make it so).
While the tag has "ms paint" in the name, that is due to Paint's memetic reputation as a zero-barrier-to-entry first tool of the inexperienced, not a literal assertion; the picture doesn't have to be made in MS Paint, and inversely, not every picture made in MS Paint qualifies for this. The pictures has to look so bad to the viewer they would say "why this picture is drawn by 10-year-old in MS paint?", either intentionally or not.
The example on the left is a comedic post that qualifies for this tag, despite the fact that it has not been drawn in Paint – one can tell from the rotated text, which Paint infamously does not have a tool for, the point is that it invokes the atmosphere. The one on the right, however, was genuinely drawn using Paint, but does not qualify for the tag. You can clearly see the quality differences between both.
Discussion on whether or not to keep the tag is at topic #42566, and tagging pictures that you simply don't like with it is unacceptable behavior.