Explain the concepts 沙雕 and 沙雕图 I came across these two words recently.

Literally they mean sand sculpture and sand sculpture image.

They are now internet slang for unrelated concepts seemingly.

My understanding is that they are used to refer to some kind of meme, but I'm not quite sure what kind.

Memes where someone is doing something silly or foolish.

The word may have been chosen as the pronunciation is similar to 傻屌 so there may be some connection there.

Can anyone provide more detail into these two internet slang terms ?
In addition to meanings explained by other answers, 傻屌 are much more offensive and vulgar than沙雕.

沙雕 is generally used humourously to describe weird or stupid but funny behaviours or lame jokes, as with a lot of memes. It is still vulgar but I would not call it offensive (unless it is directed to a person as an insult and used to avoid censorship of 傻屌). You will see mainstream websites use 沙雕 (e.g. 沙雕网友) liberally (not in serious news, though).