Empty paper

Could my creativity be related to madness? I dare hope not, for last night, while happy -- resurgance of sanity, like a shower temporarily flushing away a day's worth of sweat, dirt, filth -- I sat staring at a blank paper not able to come up with more than 30% of an idea ... more than on the tip of my tongue, but more like:

A guy walks into a bathtub with a duck and a rabbit ...

and there it stops. I generally don't think of jokes like this, but my mind is usually a torrant of ideas, some complete and some bits, pieces, still needing care and assembly.