Tesla coil, or High frequency AC source
Place the florescent tube close to (but not touching) the HV source. The tube will light. Be careful not to get a streamer from the tesla coil to strike the end of the tube.
Some Plasma globes are powerful enough to light a small florescent tube.
Van de graff machines will light florescent tubes intermittently.
Do not hold the tube in your mouth as is the tube fractures you may get a mouth full of glass and mercury.