Good tip, thank you! I actually do it a little differently myself after playing around and trying to figure out how to get my Boba's into the carto filler without leaving it overnight. I leave the condom on the connector end of the carto, then put a few drops into the carto. This is where Boba's will usually just sit atop the filler, not wanting to soak in. I tried sucking on the carto like was recommended, and it did work, although I found it was easier for me to do this: just put the condom back on the mouthpiece end and quickly pull it off (this creates suction pulling the liquid down into the filler). I repeat this until the liquid is pulled into the filler, then add a couple drops, and repeat. Still not exactly hassle-free, but I found that I can fill a carto much quicker this way.