I once rode over a can on my bike and the can clamped itself to my front wheel, caught on the stays of my mudguard which pulled the guard onto the tyre bringing me to rapid, undignified halt. Luckily I was only going slowly. I won't fall for that one again!
Ah, that brings back some painful non-can related memories... as a youngster I recall cycling across our local park absolutely as fast as I could possibly wind my sturmey-archer geared "racing" bike up to - probably in the region of 20mph with a favourable tail wind... One afternoon, the stays which held the front mudguard up mysteriously detached from the mudgard, and proceded to wrap themselves around the wheel, eventually (for "eventually", read "about 5 nanoseconds later") buckling the wheel severely....
As far as I was concerned, the front of the bike did 2 things: It stopped instantly, which is always a disaster on a pushbike; but like a recalcitrant horse facing a fence, it also dipped its nose down, guaranteeing the erstwhile rider a flight of Wright Bros proportions. The style of pavement at this particular park was a tarmac central section, with a stones-in-cement style decorative edging. I can attest to the fact that you can achieve an excellent gravel rash from such a style of "kerbing".
The worst thing, after the bleeding had stopped and the pain receded to manageable levels, was the fact I couldn't even push the bike the remaining 1/2 mile home, it had to be carried.