Psychomania (1971)

Synopsis
An annoying devil-worshipping British biker gang calling themselves "The Living Dead" decide to take their moniker to heart when their leader commits suicide and is brought back from the dead in an occult ritual, thanks to a Satanic pact. Realizing that becoming zombies could be even more fun than the usual day-to-day hell-raising, most of the gang follow suit -- throwing themselves off buildings, into traffic, walls, etc. Without the annoyance of death to contend with, the Living Dead become even more obnoxious than usual, leading to a pat solution from their leader's peeved mother (Beryl Reid). Outrageously dated and featuring loads of unintentional laughs, this is still the finest movie ever made about British zombie biker gangs and features the stately Reid turning into a giant frog. ~ Cavett Binion, All Movie Guide