TLHH3 is a three day event in the little Havana section of Miami. TLHH stand for "The Little Havana Herf" and the 3 denotes that this is the third annual event.
Gael posted a link on the other TLHH thread that will give you an idea of what all is going on that weekend. Gael is the owner of La Luna Cigars.
I was unable to attend the first two TLHHs, but I have heard from reliable sources that they were fanfreakintastic events.
Happy herfin'
Pork Chop