hey illy is your avatar Dr. Strangelove (Peter Sellers) form "Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb" (really good movie btw )
no no no tequila should NEVER be mixed with beer, just vodka yes ALWAYS vodka!
Try this (for a glass) : 1 part vodka + 1/4 part instant Coffee (dissolve it in the vodka) + 2 (or 3) parts Coca Cola (or Pepsi Cola) and be careful when you add the coke - it will bubble up