Maybe one of your local stations played it a ton, maybe your friends played it a lot at parties, but in any case what songs felt like big hits to you (even though they actually weren't)?
Rock N Roll by Avril. It wasn't even just me, everyone on that thread thought it would be Avril's huge, comeback single that the GP would really be into since Girlfriend.... and then it peaked at #91 on the Hot 100 and after two years doesn't even have 60M views on VEVO
This is from like 10 years ago but I thought American Idiot by Green Day was a smash number one hit and turns out it only peaked at 61 in the US
It sold over 1.3 million digital copies though, huge numbers for a song that was released before the digital era and with such low peak on the Hot 100.
Bitch Better Have My Money felt like a top 10 hit at the very least to me. The week it came out someone wrote Bitch Better Have My Money in the door of the elevator at my college residence hall