Slow is a slang term used for illicitly produced fentanyl (different from the fentanyl produced by big pharma, which is often used for pain management when someone is on hospice).
Fentanyl is a dangerousstreet drug that is known for being inexpensive and very deadly. Throughout the 2010s and 2020s, in the US it said that fentanyl has killed over 100,000 people (I imagine you could easily find a source for this).
'I did a shot of slow last night and Barbara had to Narcan me three times. When I woke up I was so pissed at her, not only because I was sick but mostly because it was such a waste of dope.
So you like the slow and the go? (This would be asking someone if they use both fentanyl and methamphetamine).:
To deliberately respond slowly to an instant messageconversation online in an attempt to frustrate, annoy, or make the co-respondent jealous by appearing to be juggling many conversations at the same time or to project the impression of being too busy to reply in a timely manner. This is typically achieved by putting one's phone down and performing other tasks knowing full well the other party to the conversation is hanging on waiting for an immediate reply, and that aforementioned person is edging towards homicidal thoughts towards the instigator.
"I was having a WhatsApp conversation with Mary last night and she slow responsed me throughout the conversation"
"Oh man - that's unforgivable. Ditch the bitch"