Think of the character of "Mr. Bean" or someone who always spills their coffee, forgets their keys, or trips over thin air. That's a schlemiel!
Here are some synonyms in English:
* Klutz
* Butterfingers
* Doofus
* Goofball
* Shlub
Interestingly, the term "schlemiel" is often used with a touch of humor or sympathy, acknowledging that the schlemiel's misfortune is often more amusing than malicious.