An Eskimo brownie is when someone gets a condom. Releases fecal matter into the condom. Seal off the open end and freeze it. Once frozen they use it as a dildo until melted and refreeze it.
"Hey did you hear Zack did an Eskimo brownie with his girlfriend?"
"Yeah I herd she got so lonely that she just hit an all time low and did an Eskimo brownie."