The one that flopped

This one flopped when I told it on TLEC.

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Knock, knock

Who's there?

Thomas

Thomas who?

Help! Thomas problems with my fragments.
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(As in "too" + "mas," too many.)

I told you these were bad. So how's this one?

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Knock, knock

Who's there?

Hal.

Hal who?

Halp! Hansoexposed keeps messing with my fragments!