Toothpaste pregnancy test theory

I’m not ttc or even wanting another child atm, but I have had a few really strange things happen to me that’s kinda got me confused. I took my only hpt a few days & it was negative (about 4 days before expected period). I have 2 days until my expected period is due now & I’m really curious if the toothpaste theory worked for you? If you took it was the results accurate? For those of you not knowing what it is, it’s where you put white toothpaste in a clean cup, mix it with your urine & if it fizzes up you’re supposedly “pregnant”. If it doesn’t or change in any way, you’re not “pregnant”. Thinking about doing this just for shits & giggles lol