I know an old lady who swallowed a spider That wriggled and jiggled and tickled inside her She swallowed the spider to catch the fly I don't know why she swallowed the fly Perhaps she'll die.

Assuming you don't gulp one down one on purpose, is it likely you can swallow a spider unintentionally in your sleep? "There was an old lady who swallowed a spider that wriggled, and jiggled and ...