One of those phrases that should instantly set off your
bullshit alarm. Trust is something that is earned through
shared experience and observation of another person's
behavior. 99% of the time, the fact that someone has to
explicitly tell you to
trust him means that he's planning on using you, and is trying to make you
let your guard down.
If the speaker is someone who you already trust, telling you to have faith in their ability to accomplish a certain task or get through a difficult situation, it's a different story. But if "Trust me" is implicitly followed by "with your well-being/money, even though you don't really know me", then what the speaker really means is... well, I guess leonfp put it pretty well.
Other phrases which are also generally bold-faced lies include: