This is fixed in version 2.3 of the Main Dictionary
Early versions of the Main Dictionary contained several objectionable words. When you spell check with certain misspellings, the spell checker would offer an objectionable word as an alternate spelling.
The older versions of the Main Dictionary with this problem were shipped with MacWrite II through version 1.1v4, ClarisWorks 1.0 (all versions), MacDraw Pro (all versions), and FileMaker Pro (versions not verified).