A hairstyle made popular in Saginaw, Michigan, in which a woman's hair is pulled up into a full or half ponytail and then pushed forward and sprayed, resulting in a bump of hair on the top of her head that makes her skull look convex.
Kyle: Did you have a nice time in mid-Michigan?
Kristi: How did you know I was there?
Kyle: Honey, the Saginaw Speedbump gives it all away.
Kristi: How did you know I was there?
Kyle: Honey, the Saginaw Speedbump gives it all away.
by Kate Charlton October 7, 2008
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