I recommend Social Suicide. 
 ***** 
 Well, i didn't laugh my pants off while reading Social Suicide. However, the fun was constant throughout the book. I chuckled time after time! I didn't even try to guess who the culprit was because i'd rather enjoy Hartley's wacky investigation on the murder. and I did. :) 
 Sam's a standout in this sequel. I lover her deadpans! and Chase... Ha! Even i will be as clumsy and assuming as Hartley was when it came to him. C'mon, Gemma Halliday, give me more Chase swoon moments! but i already love Hartley's hit-and-miss with him. =) 
 Both Deadly Cool and Social Suicide are equally good, but i enjoyed this sequel a little bit more. Just a little bit, because up until now, i could not remove from my memory the hilarious bedroom scene from book 1. LOL