1. Bare Buns Fun Run West – Issaquah, WA
Now in its 19th year, this clothing-optional 5K challenges runners with a dirt course up Tiger Mountain, located outside Seattle. Fraternity Snoqualmie, a family nudist park, sponsors the event, whose tag-line is “Be brave, be tough, beat the mountain in the buff!”
2. Doughnut Run 5K – Ames, IA
The Doughnut Run, put on by the Iowa State University Triathlon Club, rewards participants for eating Krispy Kreme doughnuts at designated stations on the route. Runners earn subtractions from their finish time for each doughnut consumed and successfully held down.
North Carolina State holds a similar run, in which participants must run two miles to a Krispy Kreme store, consume a dozen doughnuts, and run back to the start.
3. Fat Boy 5K – Baton Rouge, LA
The Fat Boy 5K groups runners into three divisions based on weight: Clydesdale, for runners between 200 and 230 pounds, Super Clydesdale, for runners between 231 and 260 pounds, and Ultra Clydesdale, over 260 pounds.
Runners have the option of competing as a team, but members’ combined weight must be at least 650 pounds. The event provides refreshments like doughnuts, chocolate milk, beer, and coke.
4. Fremont 5K and Briefcase Relay – Seattle, WA
Teams of five compete in this 5K relay, passing a briefcase full of canned food from one teammate to the next. The cans are donated to a local non-profit, and participants are encouraged to dress in their own interpretations of “business attire.”
5. Chase the Gorilla Down Argilla 5K – Ipswich, MA
Put on by the Ipswich YMCA, participants in this road race chase a person in a gorilla suit, nicknamed Argy. Argy sticks around after for photos, but the gorilla’s identity is a well-kept secret.
6. Beat Beethoven 5K – various locations
Instead of competing against each other, participants in the Beat Beethoven 5k race against Beethoven’s famous Fifth Symphony, trying to finish before the last note of the 32-minute piece. The race has has caught on across the US and Canada, and various cities now hold their own versions. The music is piped in along the course or, like in Covington, KY, played by a live orchestra.
7. Pajama Run 5K – various locations
Several US cities host pajama runs, nighttime races run in pajamas. Participants tend to get creative with the pajama concept, wearing footie pajamas or nighttime face cream. In Charleston, SC, the race is followed by a pajama party, and benefits cancer research.
8. Red Dress Run – various locations
These runs are put on by chapters of the Hash House Harriers, a social drinking and running club. The events draw both male and female participants, and involve a significant amount of cross dressing, hilarity, and drinking. They’re essentially massive, costumed pub crawls.
The largest Red Dress Run is in New Orleans. About 2,500 people registered for the “three to four” mile run in 2009.
If you’d rather be pedaling, check out 8 Quirky Bike Rides Across the US.