Improvisation in film is an iffy prospect—results can range from insulting self-indulgence (the worst of mumblecore) to the funniest thing you have ever seen ever since you came out of your mom's hilarious vagina (the best of Christopher Guest). Luckily, Matt Walsh (director/writer/actor/joke scientist/"ohhh, that guy"/cofounder of Upright Citizens Brigade) has figured out the formula. High Road—Walsh's largely improvised but cannily sketched road movie about a pot-dealing fuckup who befriends a teenage runaway—is both giddily funny and painfully human. (Egyptian Theatre, 805 E Pine St,, 9:30 pm, $11)