Two idiots spit pan on me on the Highway while riding

I was on my way to Bangalore from Hyderabad on my Himalayan. At one point I saw three guys on a unicorn(without any helmets), I got a bad vibe from them, so I just ignored and sped along. After a km or so I noticed they were catching up to me, as I didn't want any drama, I sped up. After 2 min I got a call, so I slowed down, attended it and started again. Now these guys overtook me and the two guys behind bent their whole body sideways and spit pan or whatever they were chewing on me. I was literally behind them like 100m or so. And they were laughing and continuously checking me. I was completely in shock and I didn't understand anything happening there. A lorry guy beside me was shouting at them but they just drove off. After some distance they took a u-turn, I just flipped my finger to them and moved on. I'm not sure if these kind of people even think before doing something like this. The remaining ride was just me riding with an empty mind thinking why it has happened to me.