Roger Zelazny and Alfred Bester. 'Fast, funny and furious sci-fi' is probably the best summary of their posthumously published colloboration 'Psychoshop'. Alfred Bester's other books, 'Tiger, Tiger' (also published with a different title 'The stars my destination') and 'The Demolished Man' are also pretty fast and furious, and occasionally funny.
Not sci-fi, and as a dedicated fantasy hater I came to Terry Pratchett's discworld series late in life, and loved it: maybe he'd like Soul Music, since that's a 'stand-alone' and doesn't need you to read the others in the series? Also, its seriously funny.
Your DS sounds like me when I was 15, and indeed my husband: we discovered that we'd owned the same books when we were that age, which is particularly impressive considering that we grew up in different continents and in very different cultures (and also very romantic :)
The one book that he loved growing up that I'd never heard of was 'Cosmic Banditos', by AC Weisbecker. The first amazon review is a good description: sub-atomic physics with drugs and high-calibre firearms. Re-reading that description, I'm not sure that is a good recommendation for anybodys DCs, but apparently DH read it as 15 and survived to grow up into an upstanding citizen.