A rather rotund house pet (eg. cat) due to it's contant hoovering up of chips, raisins, crumbs from peanut butter on toast and anything else it can get it's gums around.
Man, that's not a cat. It's a house hippo!
by Tall Trav November 11, 2006
The House Hippo is the fictional subject of a series of television adverts intended to educate about distinguishing fact from fiction in advertising.

The advertisement goes as follows:

The North American House Hippo is a fictional creature that can be found throughout Canada and the Eastern United States. The House Hippo is a very timid creature and is rarely seen. While normally a quiet animal that prefers to stay unnoticed, the House Hippo is very territorial and will defend its territory if provoked. The House Hippo comes out at night to search for food and water. The favourite foods of the House Hippo include chips, raisins and the crumbs from peanut butter on toast. The House Hippo will come out at night to search for materials for its nest. They tend to build their nests in bedroom closets with mittens, dryer lint and bits of string.The House Hippo sleeps 16 hours a day, only coming out to search for food and water and materials for its nest. Also, due to their timid nature, they chose to only come out at night while you are most likely are sleeping.

The House Hippo Commercial series was made in Canada to make children aware of how gullible they can be and to teach them to not believe everything they hear. The television advertisement was produced by the Concerned Children's Advertisers (CCA) of Canada, and is currently adored by Canadians of all ages.citation neededUnfortunately, many of the kids who should have received the message currently suffer from ADD and do not catch the end of the commercial that explains the fictional characteristic of the House Hippo. Evidently this results in the wide spread belief by many ignorant and stubborn people that House Hippos actually exist. A popular example is Bradley Wakler, a 15 year old boy with E.S.L. who could not distinguish the meaning of the last sentence, and needed phycological treatment to eradicate the belief in House Hippos.
Oh look, the House Hippo advertisement is on.
by --lynn-- August 12, 2006
lives in canada and eastern united states, house hippos eat chips, raisins, and the crumbs from peanut butter on toast. they make their nests out of dryer lint, lost mittens , and bits of string. the nest has to be very soft and warm, house hippos sleep, 16 hours a day.
by mike hunt September 29, 2003
A make believe creature made to troll Americans and is a meme in Canada. There are commercials portraying a frog-sized hippo that is unwanted and wanders thy home.
Canadian Friend: "Dude there was a house hippo in my bathroom this morning!"

American friend: "A what?"
by blackwater0 December 15, 2020
A house hippo is slang for a very large and obese partner in a relationship. Wandering around the house, you'll never know what it'll eat next.
Craig: Hey, can you bring some chips over for the game tonight?
Paul: Sorry bro, we are all out. My house hippo ate them all again.
by Pharmamemes.ms February 2, 2020