Import the whiskey glass into the scene. Then go into your scene manager. Click the arrow on the whiskey glass prop and select whiskey. That is the liquid in the glass. Select the whiskey glass and press the "R" key on your keyboard to bring up the scale gizmo. Simply grab the blue "Z" scale and pull down to make the liquid drop in the glass. You can make the liquid go all the way to the bottom of the glass or as far as you want to make it look like the character is drinking it. You can also reverse the action and make it look like the bartender is filling the glass. I hope this helps.