Set up the speaker and crystal glass. The glass should be very close to the speaker for maximum sound reverberation. However, the glass should not be up against the speaker or touching it.
Determine the inherent pitch of the glass. Dip your finger into the cup of water and run it along the top of the crystal glass until it sounds its specific pitch. This is the pitch of the glass and the pitch that will cause it to hum and even break when loud enough.
With the sine wave generator, play the pitch of the glass. In order for this to work, the pitch generated on the machine must be the exact pitch of the glass, so a couple tries may be necessary.
Gradually increase the volume of the speaker. Increased volume of the correct pitch will cause the glass to break when it can no longer handle the reverberation of its own pitch.