The title's a mistranslation.
BUKIYOU (adj-na,n) (1) clumsy; awkward; unskillfulness; lack of ability; (2) tactless; awkward (e.g. socially); gauche; (3) (arch) mean; cowardly; base;
Ueno's the latter, not the former. She doesn't trip or drop things. Instead she'll try to make you drink her processed urine, eat her underwear and test her Pervert Detector by groping her. (It goes off whenever she puts it on her own head.)
Oh, and she does all this while screaming, ranting and gloating. She's a schoolgirl mad scientist who can probably control black holes and talks like a villain, although her schemes almost always backfire. For starters, she's capable of thinking up ideas so outrageous that they embarrass even her. She'll try to do something appalling, but start stammering and glowing bright red at the crucial moment.
She's doing all this because she's in love with a boy called Tanaka. (She can't say so.) For the most part, he reacts like a normal person, which drives her nuts since she keeps assuming he's a sex-crazed anime schoolboy pervert. There are, though, times when he's inhumanly stupid (e.g. thinking an obvious robot is the real Ueno) or dense enough to exasperate the entire room (e.g. assuming he's offended a girl who turned red when he said she was cute).
This isn't an ecchi anime, incidentally. It's not sexy and the character designs look like a cartoon for six-year-olds, with Ueno being a fanged goblin with intelligent hair. (When she's surprised or shocked, it'll react too.)
Is the show funny? Sometimes, yes. It's mostly just outrageous, but Ueno's manic energy is entertaining. I also liked the intelligent pet made from her tights in ep.4. (It's nervous of Tanaka and it likes grabbing on to legs.) It's cute. Besides, you've got to admire the brazen horror of Ueno's discussion and multi-stage schemes in ep.7 for tricking Tanaka into eating her knickers.