The past tense of dig is dug, surely jig and jug follow the same rule. The basis of the English language is far more complex.
The verse below is extreme frippery. Reflections of musings of three letter words ending in ‘ig’ that have a corresponding ‘ug’ ending word.
Big bug in the fug
did not dig the fig
He dug the Mig on
A rig.
Pig the pug plays tig
On a rug and does
Jig in a jug on
A tug
The first draft was constrained by four single syllable words per line, the first letter of the three letter words, alphabetically, dictated the order of the lines, and ug after ig.
A big bug did
Dig and dug not
A fig in the fug
Nor jig in a jug
Mig on a mug
Pig the pug goes
To rig a rug
For tig and tug
theINFP 
Dear Robert,
HaHa! You are being clever and witty here!
And I wonder why you have titled your post “If”.
If pun is not intended for this post, then fun is definitely designed or desired for it. Well done!
In essence:
I did dig your wit.
And laughed in a fit.
English is indeed a fast-evolving language, but not always in a good and unproblematic way, for my following analytical post presents in its own witty way:
https://soundeagle.wordpress.com/2013/06/24/use-with-caution-or-not-at-all/
Yours sincerely,
SoundEagle
Thank you, if was really the start of the first sentence. When I shared the post of FaceBook, I added, Sunday nonsense. Maybe this is a better title.
Are you turning this into a book of poetry? I like it.
Thank you 🙂
Fun reading !
Thank you 😎
A painter plays with paint, you are a wordsmith playing with words for others to enjoy
Thank you