"I am Dave! Yognau(gh)t, and I have the balls!"
(The Yogscast's signature salute)
Lewis has a friend called Dave who likes to tazer him sometimes. We're not sure if Lewis enjoys this. Lewis also explained that Dave has large speakers in the back of his car.
The phrase, "I have a friend called Dave who...", is often a sign that Lewis is about to start rambling one of his anecdotes.
Every time Lewis brings up an adventure with Dave, he is getting one step closer to his midlife crisis.
Dave could also be a reference to DaveChaos, another recently added member of the Yogscast.
Dave was also mentioned in the treaty of Dong Hill as being the great great grandfather of Simon's Minecraft character Honeydew. So Dave may be a minecraft character at the same time.