What Goes Up... is the eleventh episode of Season 2 of The Brady Bunch, and the 36th overall episode in the series. Written by William Raynor and Myles Wilder and directed by Leslie H. Martinson, it first aired 11 December 1970 on ABC.
Bobby develops a fear of heights after falling out of a tree.
Peter and some of his friends have started a club, meeting in a treehouse. Bobby wants to join, and although they think Bobby's too little, Peter convinces them to let him join as a junior member, who pays dues and does menial jobs for them. Climbing up into the treehouse for the first time, Bobby slips, falls, and sprains his ankle.
In an attempt to cheer Bobby up, Mike and Carol buy him a parakeet for company. However, the family dog Tiger scares the bird. After several days of bed rest, Bobby begins to climb up into the treehouse, but is afraid. Not wanting to show his fear, he feigns ankle pain.
Greg starts to suspect Bobby is deliberately feigning prolonged ankle pain to avoid any activity that involves heights, when he offers to take him biking down a hill Bobby always enjoys. He even offers to let Bobby use Greg's bike, which has hand brakes, so Bobby won't have to use his sore ankle to brake if the need arises. Mike and Carol notice that when Bobby comes downstairs for dinner, he's not showing any signs of limping.
Mike and Carol later talk to Bobby about going on a mountain hike trip, something at which Bobby has always been good, as he was the first to reach the top on previous trips, but Bobby declines to go, saying his ankle is still sore. Mike uses a ladder to pretend to fix a shutter on the second floor, and asks Bobby to bring him nails, but Bobby foils it, simply giving them to Mike from the window. The family then obtains a trampoline, and Peter, Jan, Cindy, and Alice take turns bouncing on it, while Bobby watches from his room. He still shows no interest in bouncing himself.
Bobby's fear is finally overcome when Tiger scares his parakeet out the window, and he is forced to rescue it from the top of the swingset. He still declines to join Peter's club, because he doesn't enjoy the duties that come with being the junior member, and starts his own club, with Tiger and his parakeet as his first two members.
- Maureen McCormick (Marcia) does not appear in this episode.
- In the trampoline scene, Carol calls Peter by his actor's name, Chris, and Greg calls Jan by her actor's name, Eve.
- This was the final filmed appearance of Tiger.