I was crossing Donny cas once when every man and his dog was flying. I'd asked for a VFR crossing although it was very claggy, it was good enough to dodge around the clouds. After getting a dozen or so crossing contacts in about two minutes from an obviously 'concentrating' controller he asked me to remain at my altitude to maintain seperation from another contact.
This would put me IMC so I called 'Present altitude puts me India Mike in 30 seconds, request change of flight plan to IFR.'
'G-*** remain VFR but cleared IMC'.
Still got to figure that one out....