According to a video interview I saw with Carlos Santana (in an exhibit at the Music Experience Museum in Seattle), Carlos was on acid during his performance at Woodstock. He'd apparently mis-timed the LSD and ended up baked on stage. He said he felt snakes growing out of the guitar. But somehow he pulls it off--and makes some awesomely classic guitar faces while he's doing it.
Note that Michael Shrieve, the drummer, was only 19 years old at Woodstock...
---o0o---