TIFF with a tag with incorrect type but still readable (TIFF readers should accept BYTE, SHORT, or LONG values for any unsigned integer field.
With an Hexadecimal Editor (e.g. HxD) a TIFF file can be edited in order to change a tag type. Look for the tag signature and change the value in the type field with an invalid but compatible value. For example, change the type of a SHORT typed tag to BYTE.
A tag signature is an 8-byte hexadecimal value where its two first bytes contain the tag id, the two following bytes contain the tag type and the 4 last bytes contain the tag cardinality. The TIFF reference documentation contains a list of the available tags, with its ids, accepted types, and valid cardinalities.