“pi=10, it also equals 3 and e=3 so pi=e!”
When talking about safety factors, the informant, an engineering student, shared the joke. Because engineers are always concerned about the safety of the users of their products (because getting sued is no fun) and like to account for the things more difficult to account for, one way to introduce a safety factor is to make pi equal to 10 in all calculations. This massive rounding then prompted the follow up of simply rounding e (~2.718) and pi (~3.14) could simply be rounded to 3 for simpler calculations and that error would be accounted for with the safety factor.
This joke has some practicality to it by reminding engineers to have large safety factors to ensure the safety of their designs, it is also a joke on the rather flippant view of numbers that engineers have as it doesn’t always need to be precise but simply overkill enough for the application. I also relate this to the idea that engineers are lazy and so create processes and machines to ensure they can be lazy at the desired times. Multiplying or dividing by 10 is about as lazy as it gets in math.