The only real context through which it is suitable to make use of the phrase "mostest" is straight away after the words "I love you the". "Bestest" can also be suitable During this context (and no other). Stack Exchange network is made of 183 Q&A communities like Stack Overflow, https://financefeeds.com/swiset-data-reveals-what-traders-are-really-doing-in-prop-firm-challenges/