Ever since the Great Recession, interest rates have been so low that Cramer hasn't been recommending investors to buy bonds. That isn't because "Mad Money" is just about stocks; it is because stocks and bonds play very different roles in a portfolio.
"In general, for the last few years, even when the stock market has been getting absolutely pounded, bonds simply haven't represented very good values versus equities," Cramer said.
But that doesn't mean there isn't a place for bonds in a portfolio. They play an essential role in investing, especially as investors get older.
How much of a retirement portfolio should be kept in bonds versus stocks? Cramer broke it down by age:
- 20s: None
- 30s: 10 percent of your retirement fund; 20 percent if you are conservative
- 40s: 20 to 30 percent
- 50s: 30 to 40 percent
- 60s: 40 to 50 percent bonds
- Post-retirement: Increase bond exposure to 60 to 70 percent
Read MoreCramer: Bond exposure by age—protecting yourself from market volatility
Additionally, Cramer doesn't subscribe to the "buy and hold" mantra that most do. He's all about "buy and homework." That means that no matter how confident one is in a company, they must keep checking up on it regularly to make sure nothing has gone wrong in the story.
When taking these investments into consideration for the long term, one thing became very apparent to Cramer: if you know what you're doing, a bear market is an opportunity.
A bear market refers to when the averages are down by more than 10 percent from their highs and seem like they could go lower.
"What I am saying is that when you are faced with a bear market … it probably makes more sense to start buying most stocks, rather than selling them, as long as you are willing to take some short-term pain," Cramer said.
The key is to be patient enough to take advantage slowly — so you don't buy too close to the top — and to be careful about the stocks chosen in a bear market. Do your homework and pick the stocks of companies that are doing well, or doing OK and could be doing better in a stronger environment.
And to really take advantage of a monster decline, Cramer said to keep cash on the sidelines to make your move. Then you can buy high-quality stocks in small increments on the way down.