People that have gained an ACTUAL 10lbs since high school, and are HUGE in their own minds now. People who THINK they can lift "enormous" amounts of weight, always exaggerating greatly.
TSInLS1, the UN-legitimate AAU World Record Holder for deadlift in the 17-18 year old range for his bodyweight.
It's an slang very common in some kinds of situations.
You are about too ask a gorgeous woman out, you're not so sure about that, because you think "Oh, I can not as her out, my wallet is too small for my 50's".
It means that you are thinking that she is too good for you.