This segment appears on the first episode of Brainiac: Science Abuse.
First Test Edit
Since blowing a car up would be cruel, they chose to blow up a caravan. Hammond places a cell phone in the petrol fume scented caravan that has petrol all over it. After getting out, he dials the number and after a few minutes, gets no result and tries using more phones.
Second Test Edit
With 6 mobile phones, a few couple on silent with buzzing, Hammond heads inside, yelling at the Brainiacs not to phone as it won't be funny. After putting them in, he and Brainiacs dail the number and still get the same result.
Third Test Edit
Since the mobile phones won't set the caravan on fire, Hammond has a Brainiac wear nylon clothing and dance in a bucket while wearing the nylon clothing. After a few seconds, the Brainiac touches the fuse and the caravan explodes.