“We might as well stock up.”

You're shopping at a grocery store with your son. You see that toilet paper is on sale there, so you think it's a good idea to buy a lot of it now. You say:

We might as well stock up.

(someone) might as well (do something)

Saying that you "might as well" do something means that:

• you think it's a good idea to do it
• it's easy to do

In the example above, buying a lot of toilet paper while it's on sale is a good idea because it's cheaper. It's also easy to do because toilet paper isn't very expensive or heavy, and it won't go bad like some foods would.

Another example of "I might as well" is:

I guess I might as well stick around and have one more.

stock up (on something)

To "stock up" means to buy a lot of something, so that you'll have it ready.

Use "on" to express what you're buying a lot of:

Make sure to stock up on food and water before the storm hits.

Cigarettes are cheap over here, so a lot of people who visit stock up on them.

People usually stock up on consumable goods, like food, drinks, batteries, paper towels, etc.