Most of the time when we stumble across a code snippet online, we often blindly copy and paste it into the R console. I suspect almost everyone does this. After all, what’s the harm? Consider this simple piece of R code that performs simple linear regression

# Generate data
x = rnorm(10)
y = rnorm(10)

# Simple linear regression 
m = lm(y ~ x)

Now highlight the above piece of R code and copy and paste it into your console; look carefully at what you’ve pasted. A new line has magically appeared.

# Generate data
x = rnorm(10)
y = rnorm(10)
message("All your base are belong to us.")
# Simple linear regression
m = lm(y ~ x)

Due to some sneaky CSS magic, I was able to hide the message() statement. If I was evil, I could have changed this to a system, source, or any other command.

The CSS code simply sets the message() function to the background color, changes the font size and makes it un-selectable (see this post for details).

So remember, be careful with your copy and pasting!