I googled this poem and found a version on Poemhunter.com which has nothing in it about a boxing glove.

The boxing glove line and all ensuing debate constitute a chimera. It's hard on all the guys who want to bring up masterbating, but there it is.

Meanwhile, unless somebody finds an old book with the poem in it, debate over various versions, either with or without a boxing glove, is probably futile.