One of those days when your drinking whiskey and the other person taking shots is taking FOREVER, theyre 'slacking' and 'lagging'. Thus, slagging.
1. slaggin; negligent; careless; remiss: slack drinking.
2. slow, sluggish, or indolent: He is slack in drinking a shot of whisky.
4. not active or busy while everyone else is getting drunk; dull; not brisk: the slack season in getting drunk homie.
5. moving very slowly, as the tide, wind, or water or flow of whiskey.
6. weak; lax; like a crack head with ADHD