have no idea
mooncalf
wrong end of the stick
misconception
misken
thought bubble
misconceiving
throw out
take for
faultily
misperceive
mishear
demented
see
misassumption
counteridea
misinterpret
mismean
misdiscern
misclaim
misimplication
undeceived
disabused
under the impression
mispick
miscomprehend
misplan
misbrief
misapprehend
clear up
put two and two together and make five
uninformedly
misguidingly
misassume
miscalculate
pervert
misexpound
wrongmindedness
misestimate
malobservation
misexplicate
misconceivedly
false step
hallucination
misimputation
delusion
notionlessness
fudge
confuse
ass-backwards