I've been googling for user experiences with supplements containing Lactobacillus Reuteri and i've found weirdly disturbing forums where people were reporting 50% increase in testicular size, hair growth and testosterone level after few weeks of usage. It felt like someone is trying to sell these supplements to teenagers with low self esteem by creating fake reviews or something... Some of these were on reddit.
After having the same WTF reaction I came across this mouse study: Probiotic Microbes Sustain Youthful Serum Testosterone Levels and Testicular Size in Aging Mice. Sounds like the L. reuteri supplement made a pretty dramatic difference in preventing hypogonadism as the mice aged. Quite a jump from that to "2 weeks to make your balls bigger", but still, it's pretty interesting.
What the hell?