It takes a lot for a mainstream comedy to get an ‘18’ rating these days, but getting a three-year-old nutted on cocaine seems to have done the trick. The first ‘Harold & Kumar’ film was a sweet, low-key stoner comedy, the second a crass slapstick romp and this third instalment falls somewhere between the two. Like the first movie, it’s firstly a well observed tale of friendship, as our estranged heroes (John Cho and Kal Penn) bond over bongs and blunts while searching for the perfect Christmas tree to appease Harold’s Latino gangster father-in-law (Danny Trejo – who else?). As before, the film’s strengths are two likeable leads, a self-mocking cameo from Neil Patrick Harris and some witty observations on race in America, bolstered here by a surprisingly inventive use of 3D. It’s not quite smart or funny enough – and some of the gross-out gags cross the line – but for all its pretensions to bad taste, this is surprisingly heartwarming festive fare.