The phrase "warm lap" refers to a situation where someone has a comfortable and cozy space on their legs where another person or sometimes a pet can rest and feel warm and safe. Full definition
These loving dogs can range from young dogs to «Seniors» who are just looking for a nice warm lap. (ta-kodabostons.com)
He loves going on adventures in the car, on long walks, sitting in warm laps, and sleeping under the covers. (emmakmorris.com)
Ebooks are of little interest to cats, other than that ebooks tend to make their humans sit still for hours on end, thereby exposing warm laps for extended periods of time. (smashwords.com)