Hampster is a common mispronunciation and to a lesser degree, misspelling of hamster.
The extraneous p is caused when the speaker fails to halt breath between syllables, causing the lips to pop from the sudden change of the internal air pressure.
How does one avoid this? There are plenty of ways to. Make the m as short as possible, deliberately pause exhaling when opening the lips, or think of the syllables as separate words, for example, ham stir fry.
Getting the admin of hampster dance to fix the spelling would also be a step in the right direction.