In Habeas Corpus (1928), Oliver Hardy shinnies up a post to read a street sign at the top. He reaches the top only to find a sign that reads, "Wet Paint." He can see now that the post has been freshly painted and the paint has left a thick white stripe running down the front of his suit.
This gag appeared in earlier films, including a 1920 Roach comedy called Money to Burn and a 1925 Sennett comedy called Sneezing Beezers!. Here is the scene in Money to Burn.
Laurel & Hardy used the gag again in the 20th Century Fox feature The Big Noise (1944).
The gag continued to be used by others in a variety of films.
I Was a Male War Bride (1949)