We do have 'Wordless Wednesday' but I am not sure about 'Spontaneous Thursday'? I notice that some of the bloggers have started making their 'Spontaneous Thursday' so I think it was a cool thing to do. Like the famous DJ said, " I follow you" ~~
Spontaneous Thursday is when the bloggers post or write a spontaneous sentence and it will not be explained in detail. It's just a sentence which maybe carries a lot of meanings.
So, have fun trying to figure it out!