This background character shows up twice in Spirit: Stallion of the Cimarron. From the two scenes he’s in, we see that he’s got an ego, and both times he’s proven wrong with unfortunate results.

Small role, but just enough to pick up on personality. Dude has two significant scenes in the movie, and both times we see him doing something to give the impression of having an ego and a bit of arrogance. And yet both times he’s proven wrong by a horse.

Moana(2016)

Dr Doom: I'm a lead farmer motherfucker!!

In episode 7 of Season 1 of Ted, Matty Bennette said he got drafted and was shown a movie that features Tony Randall that was about Sex Education. The film Everything You Always Wanted to Know About Sex But Were Afraid to Ask featured Tony Randall (among other famous actors). However, this film came out in August 6th, 1972. If this is the film that he was shown in the drafting process. That means the longest possible time he was in Vietnam was between August 6th, 1972 until March 29, 1973 or 8 months. However, there needs to be some massive considerations such as a buffer for when the movie could of been shown to troops, the possibility he could of been shown this very early on, his training length and the cease-fire of January 23, 1973.

As a buffer, I think it is respectable to give 30 days between the release of the film and it being shown to troops because the likely case that they had to source the film. So, September 1st. While very unlikely, he says "When you get drafted, they show you a film." Which has an unlikely but real connotation that it was shown very early on. Most sources point toward the majority of draftees spending a minimum of four months before being boots on the ground. That means, he would of entered Vietnam by December.

A cease-fire was called on January 27, 1973. The less than 70,000 US troops in Vietnam still saw combat during those final months. Yet, significantly less. That means there's a very unlikely but very real chance that Matty Bennette jerked off a dog and then left Vietnam.

This is not accounting for the fact that his MOS could of very likely been as a Scout / Dog Handler which has additional 18 weeks of AIT after Basic training which narrows his time in Vietnam even further.

Footnote: He mentions being two clicks south of the Do Lung Bridge when he had to jack-off said dog (Scout). Do Lung Bridge is a fictional location from the movie Apocalypse Now. Though, I think is just a joke rather than some kind of hint about him lying.