The phrase "to fall over" means to lose balance and collapse or fall down, often due to a lack of support or stability. It can also refer to someone fainting or collapsing from exhaustion, illness, or injury.
I don't fall over when I see a load of nasty tweets pointed at me. (bbc.co.uk)
This coat rack is also sturdy and will not fall over when full. (lemonslide.com)
Smaller dogs and cats should always travel in a carrier, which should be secured to prevent it from falling over in the event of a quick stop or an accident. (parkanimalhospital.com)