Used in many ways, "haw dewd" can be related to a greating, an outburst of excitement or just for the fucking fun of it.
person1: You just got your car towed man.
person2: Hawwww dewd. (sense the tone)
2. (enters room)
(and then a 2nd person can finish the phrase, thats team effort)
3. person1: hawwwwwwwwwwwww! (very loudly)
haw dewd in your mom dewd.