make (one's) head spin
To make one feel very dazed, bewildered, or shocked. If you try anything, I'll sue you so fast it'll make your head spin! Looking at all the legal mumbo jumbo in these contracts always makes my head spin.
make one's head spin
Cause one to be giddy, dazed, or confused, as in The figures in this tax return make my head spin. This phrase employs spin in the sense of "rapidly gyrating," a usage applied to the brain or head since about 1800.