So I play FR like 95% of the time and was a little lost here. This might be standard but I'm really not sure. I would usually fold here expecting to see 77-TT in FR. I'm readless. Whats my line?

Poker Stars, $0.50/$1 NL Hold'em Cash Game, 6 Players
LeggoPoker.com - Hand History Converter

BB: $53.75
UTG: $63.90
MP: $106.50
CO: $95.50
Hero (BTN): $115.85
SB: $86.90

Pre-Flop: 6 6 dealt to Hero (BTN)
3 folds, Hero raises to $4, SB folds, BB calls $3

Flop: ($8.50) 3 3 5 (2 Players)
BB bets $15, Hero ???


edit: here is a hand we played earlier. He called me light, but I still am readless regarding his donk bet.

Poker Stars, $0.50/$1 NL Hold'em Cash Game, 5 Players
LeggoPoker.com - Hand History Converter

BTN: $130.05
SB: $98.50
BB: $94.10
Hero (UTG): $141.80
CO: $76.80

Pre-Flop: K A dealt to Hero (UTG)
Hero raises to $4, CO folds, BTN calls $4, SB calls $3.50, BB folds

Flop: ($13) 7 6 K (3 Players)
SB checks, Hero bets $10, BTN calls $10, SB folds

Turn: ($33) 9 (2 Players)
Hero bets $22, BTN calls $22

River: ($77) K (2 Players)
Hero bets $55, BTN calls $55

Results: $187 Pot ($2 Rake)
BTN mucked 8 8 and LOST (-$91 NET)
Hero showed K A (three of a kind, Kings) and WON $185 (+$94 NET)

W/o a read I'm def giving this up. We've only invested $4 and could get ourselves into trouble.

Raise=Shove=bad. You don't get him to lay down any overpair and will see this hand quite often. Call is also bad as you will have to call a shove on any turn. And even if he's bluffing he will have like 30% equity on the flop.
--> Fold.

easy fold. well not an easy one, but its still a fold.