For something sufficiently toad-like Squats in me, too; Its hunkers are heavy as hard luck, And cold as snow,
Now we find out why the speaker hasn't joined the merry ranks of the jobless. It turns out that the reasons for his conformity go beyond external, societal expectations.
Work is a kind of societal obligation or duty. It's what is expected of us. If you don't believe us, here's an easy test: tell your parents you've decided that college and a career just aren't for you. In fact, you've decided to play bongos in the town square, work on your tan, and just enjoy life.
Chances are, their reaction (it won't be good) will give you a pretty good sense of how seriously folks take this work thing.
Not only does the speaker have the physical "toad work" to deal with six days a week, he likely feels all the external pressure of societal obligation as well.
If that wasn't enough, there's also something "toad-like" that exists in him as well: "Squats in me, too." This internal toad-i-ness is also preventing him from living a complete, fulfilling, free life.
The internal, toad-like thing the speaker has acknowledged is something in his personality, a certain sense of obligation or duty, which keeps him from turning his back on work.
This internal toad is formidable. This is a seriously thick toad. Its hips, butt, and upper thighs ("hunkers") are "heavy as hard luck, / And cold as snow."
These back-to-back similes paint a pretty intimidating picture of whatever it is that lurks inside our speaker's psyche, preventing him from living the kind of life he wants to lead.
In Shmoop's book, anything that can be compared to bad luck and bone-chilling snow has got to be pretty bad news.
Line 27 even sounds formidable. There are all those repeated H sounds (for more on this alliteration, check out the "Sound Check" section). The line, like that toad, is hard to miss and hard to forget.